So far I haven't seen any of the new books turning up on the AH on my realm, seems that Blizz may have set the droprate a little low (world epic, rather than world blue).

Also, does anyone have any early information on the drop rates of Runed Orbs and Ulduar patterns based on their first night of raiding?

According to the Armory info, Runed Orbs have a high chance of dropping from just about all the 25 man bosses/cache in Ulduar, and always drop from Freya's Gift container in 10 man.

2 Bosses down in Ulduar so far (and 2 nights full of lag-outs and crashes) and no runed orbs so far. Right now I'm really interested to see what kind of drop rate the BoE tailoring patterns have.

The HUGE undocumented change I've seen is the ability to track more than one thing at once. I was seeing herbs pop up while I was tracking fish, and one of my guildmate logged his farming alt on to confirm that he could track mining and herbalism nodes at the same time.
I'm not sure whether it's a bug or working as intended, but the change is pretty nice.

A guildmate of mine was seeing multiple tracking types yesterday (humanoid and mining). They ticketed it, and had no response but as of this morning, their tracking has returned to 'normal' (single) tracking. I think it's probable that it was a bug.

Double tracking has been a bug for a long time. You would "get" it when you did a server transfer with mining/herb and on the new server you would appear with both enabled. It went away if you did Arenas or manually selected a tracking type iirc. I imagine this is just an extension on that bug.

Just a quick note, Northrend Alchemy Research generates mixtures instead of flasks. Not certain if this is intended or not.

The alchemist caches drop mixtures too.

From what people have posted:
~6-10 of most of the different Flasks
~5-10 of various useful Elixirs
1-10 of most of the different potions one would use for raiding (Runic Health/Mana, Speed, Wild Magic)
and raw materials (lotuses, herbs, vials)

It's definitely a decent amount of consumables for an alchemist to pick up.

Intriguing. I remember threads on various forums during Classic WoW where people begged Blizzard to have bosses with steep consumable requirements reimburse us for the extreme costs. (e.g. Loatheb 1.0 giving you Shadow Resist Potions once defeated.) Odd to see it implemented now.

Or this may simply be intended to replace the zone-specific potions TBC had, in which case, bravo! We could, say, defeat the zone a few times on EasyMode, put some or all of the cache findings in your guild bank, then lean on the stockpile for Hard Modes. Hmm!

I think they're looking for a different way to alleviate the consumable requirements other than using Marks of the Illidari. To me, this seems like a better solution than dropping marks that they have to bandaid to work for every new raid instance they will release in wotlk.

This certainly adds a different dimension to the "profession perks" mechanic for alchemists, in that if you don't have an alchemist in the raid, you don't get this benefit. Correct me if I'm wrong, but new enchant formulas drop regardless of whether or not an enchanter is in the raid, right?

Bottom line is that this definitely enforces that a guild should diversify their professions in order to maximize their loot from boss drops -- though I wonder what happened to Alchemist Caches showing up from other bosses than just Freya...