Latest patch notes are up on MMO-Champion.

Priest
Holy

* Prayer of Healing base healing reduced by 15%, from 3633 - 3838 to 3087 - 3262.
* Lightwell now restores [ 1.063% of Spell Power + 9929.445 ] health over 6 sec, down from [ 1.155% of Spell Power + 10792.875 ]
* Chakra now also affects Flash Heal or Greater Heal. Serenity now also procs from Flash Heal, Greater Heal, or Binding Heal. Chastise now procs from both Smite and Mind Spike.
* Blessed Resilience now also procs from a critical hit from any attack.
* Renew now costs 17% of base mana, down from 21% of base mana.


Discipline

* Focused Will now also procs from a critical hit from any attack.
* Strength of Soul has an additional effect - In addition, when you cast Power Word: Shield on yourself you are immune to Silence, Interrupt and Dispel effects for 2/4 sec.


Shadow

* Shadow Orb Power now increases the damage done by your Shadow Orbs by 21.6%, up from 20%. Each point of Mastery increases damage by an additional 1.5%, up from 1.3%.
* Mind Sear base damage has been increased by 60%, from [ 91 - 98 ] to [ 146 - 158 ]


So finally a nerf amongst all the buffs we had been getting, with our PoH reduced by 15%. I doubt this will change how much we spam it, however. If anything, we'll just end up having to use it more often. Other Disc changes are mostly PvP based, however Blizzard is really making Strength of Soul almost impossible to ignore at this point for any discipline build.

I'm going to agree with this. I have had this in my build to test it out. On Halfus (which is a pretty decent just stand there fight) I got the surge of light buff 6 times only out of 100 plus casts of things that can proc it. Once it changes and it can crit and proc off of so many different heals including Flash Heal it might be better. Right now I don't think it's worth it.

"Prayer of Healing base healing reduced by 15%"
+
"Divine Aegis: Critical effects from Prayer of Healing now award a bonus amount in addition to the default, always-proc Divine Aegis effect."
=
We still don't know the percent of this buff to DA crit proc for PoH, but I'm pretty sure it will increase crit weight. On the other hand mastery cap might decrease as well, but lets wait for numbers.

P.S.: Seeing us, discipline priests, as well as our holy friends, using PoH heavily on most raid encounters (rough 40% healing done), don't you think that 15% nerf is pretty hard? Or maybe both specs going to get reverting,"hidden' buff as discipline is getting through DA change and PoH will remain the same after those changes?

*waits for numbers in shiver*

Edit: missed 30% CoH buff, so my bet is that DA buff for PoH is gonna be on par! Interesting.

Regarding the Haste vs Divine Hymn discussion, I did some maths on it, and yes, it looks like it's correct from what Alv!ra and the others are saying.

Formula:

You get k more ticks for a hot/dot that has m ticks at 0% haste if your haste is higher than (2k-1)/2m.

For both Divine Hymn and Hymn of Hope, m = 4.
k = 1 : 12.5% haste
k = 2 : 37.5% haste
k = 3 : 62.5% haste
k = 4 : 87.5% haste

Lifeblood (herbalism) = 4% haste
Borrowed time = 14% haste
Power Infusion = 20% haste
Berzerking = 20% haste
BL/TW/Hero = 30% haste

Alv!ra stated that he got 21 ticks. To get 21 ticks of DH, that means that k = 3 , which necessitates 62.5% haste. Borrowed Time + Power Infusion + Berzerking = 54% haste, so if has 8.5% haste from gear and talents (not difficult), then 3 extra ticks for 21 total ticks is definitely possible.

On another note, a Troll Disc Priest popping Berzerking, Power Infusion, and PWS for Borrowed Time while under the effects of Timewarp/Bloodlust/Heroism could get a 4th bonus tick of Divine Hymn / Hymn of Hope...

So you are saying your 6% proc talent only procced 6% of the time? We're shocked.

I did some crude calculations on SoL for Holy a while back here: Cataclysm Holy Priest Compendium

While Disc doesn't have Serendipity to boost the mana value, the fact that SoL now can crit roughly makes up for that fact. That makes SoL worth roughly 130-170mp5 per talent point, depending on what you declare as your alternate healing method, and assuming you cast a proccing spell once every 5 seconds on average. The calculations do not take into account the minor effect of overwritten procs.

The difference between mine and Ellyh's numbers are mainly that I disagree with Ellyh's method of calculating the HPM impact of a SoL proc. Her method involves comparing it to how much mana you would spend in the time you cast the SoL Flash. I consider it much more relevant to discuss how much mana you would spend to heal up the amount that the SoL Flash heals.

130-170mp5 per talent point compares very favorably to Mental Agility's ~65mp5 per talent point.

At the risk of being a tad philosophical, I think the goal of talent reshift was to move away from a clear-cut 'optimal spec' to having fewer choices, but all choices being viable. If the priest changes go through in PvP, they will absolutely accomplish their goal as there are far too many things you want to pick up with the points that are available.

Yes, I realise that was Blizzard's intent for the changes, and I also appreciate the effort and generally think that it's a good thing that our talent options are all relatively viable options. Still though, and this is what spurred my comment about the optimal spec, I don't believe it will ever be possible, or should for that matter, for Blizzard to create a talent tree where we cannot say where ones points are best spent given various conditions.

What I hope is happening, is that a disc priest will have to choose his spec, taking into consideration the current fights he's working on, his raid setup, his gear, and of course his dominant healing role.

This doesn't mean that we can't still make analyses and discuss which talents are worth taking in which situations though. For instance, on the SoL debate; seeing there is some theorycrafting debate on it, I may pick that up when the changes go live, and then leave it again if I find us struggling on a fight where I don't benefit a lot from it (likely a fight with a lot of consistent raid healing).

It's all well and good that we get more viable choices, but in my book that also means we will have to adjust more frequently as we go along, in order to maximise our contribution to the raid.

I'm personally swapping in the major glyph, Glyph of Scourge Imprisonment for Nefarian as well as the +5 yard range minor that Staciokaite mentions. Makes it a lot less time-consuming to properly control my skeleton, especially if something (such as our resto druids use of Tyrande's Favorite Doll ) breaks it.

I can't see any confirmation of multy-Graces in the last banch of PTR patch notes (both mmo-champ and Russian ones)... Seems to be out of the list...

I have noticed alot of people saying Int > Spirit > Crit > Mastery > Haste. Do we need haste at all?

I'm curious about whether or not it sounds crazy to run with 0 haste, I tried it on cho'gall, 2healed it with a resto druid and we had no problems, but would my healing have been more effective with haste? I ranked fairly high so I was just curious about whether or not haste is even needed at all for disc healing.

***I was raid healing while the resto druid tank healed

Here is the log from the attempt:
World of Logs - Real Time Raid Analysis

I also run 0 haste and have had lots of success with healing, mana longevity. From a WoL standpoint, I am extremely high up there, owning the #1 HPS for any class on both Omnitron(lol) and Nefarian(more legit) in 10 man. I have about 1% haste...you will have 25 regardless through shoulder enchant and likely a bit more due to the only epic bracers being either haste/mastery or spirit/haste. I don't find the stat very useful in any way.

There was some argument that mastery was slightly better for aoe healing than disc, but with the extra bonus to PoH from critting coming, I am fairly certain crit will be further elevated beyond the other two stats.

As far as haste goes, I've said this before, but it strictly depends on comfort with mana. Having little haste, but lots of int/spirit/crit/mastery leads to slower casts but much higher healing/mana spent. This is great for longer fights with consistent damage. I have yet to encounter a fight where the speed at which you cast is extremely significant, but, if there is such an encounter, haste may have a bit more value.