From what I can gather, most Mages will be using Glyph of Fireball and Pyroblast until they are reasonably decked in full Epics and Heroic Epics. Once their crit is above 34%, they will most likely lose the Glyphs of Fireball and Pyroblast, and pick up Glyphs of Living Bomb and Frostfire Bolt to make better use of the Mastery stat.
Fireball will always be used in a Fire Mage's DPS rotation regardless of the amount of Mastery you have. The DoT effect from Glyph of Frostfire Bolt only stacks up to 3 times, and even with the +15% damage increase, it's damage still isn't comparable to that of Fireball's, and as such, it should only be cast 3 times initially to stack the debuff, and once again every 10 seconds to keep the stack alive, using Fireball as the primary nuke.
I believe Mana conservation will be a factor we will need to be more aware of early on in the expansion, as with the reduced combat ratings, will come less mana return from Crit's that don't happen often enough to make Master of Elements a viable Mana Regen stat. With the most recent change to Arcane Concentration, whereby the Clearcasting proc is no longer consumed by Hot Streak or Scorch, I believe this will be an extremely good Talent to pick up.
I don't believe Pyromaniac will be of as much use as everyone seems to believe it will be. While it will be much, much easier to have 3 or more targets taking damage from your Fire DoT's with the use of the instant Flamestrike, ranged Blast Wave and Impacted Fire Blast's, I believe many of you are forgetting the strong emphasis Blizzard has placed on the need for Crowd Control in Cataclysm. I personally have not seen Cataclysm raids, so I may be speaking out of line here, but I don't believe there will be enough of an opportunity for this Talent to be viable, except for possibly a few Trash pulls that aren't CC'd correctly.
Having said that - the Improved Fire Blast and Impact Talents aren't something to avoid for single target boss fights due to the range increase. The +8% chance to critically hit is a nice addition to the talent and one I often find using in my primary rotation to further stack an Ignite, or provide me with that 2nd almost guaranteed crit for my Improved Hot Streak proc.
Cauterize will be extremely useful very early on, as it will allow you to make mistakes often and get away with it relatively unscathed, and avoid insta-gib abilities that appear to be present on a number of the bosses in Cata, however given decent enough raid awareness and knowledge of the mechanics behind such abilities, I don't believe this to be enough of a reason to make it a raid viable Talent.
I believe this will be the spec and glyph build Fire Mages will be running with in mid-end game 1st Tier raid progression.
Fire Mage - 7/31/3