The gear list is intended for fighting anything, using Greater Arcane Elixir, Wizard Oil and Flask of Supreme Power (+ Major mana potions and Demonic / Dark runes), using either the Winter's Chill spec or the Arcane Power spec. There isn't enough hit gear out yet for there to be a different gear set for trash and bosses, but do keep in mind that you deal zero damage if you're out of mana and need to gear accordingly for fights where mana may be an issue for you.
The list
Helm: Eternal Crown of Frozen Wrath (World Drop)
Neck: Choker of the Fire Lord (Ragnaros, MC)
Shoulders:Shoulders with +30 (World Drop)
Back: Cloak with +21 (World Drop)
Chest:Robe of the Archmage (Craftable, LBRS)
Wrist: Wrists with +20 (World Drop)
Weapon: Azuresong Mageblade (Golemagg, MC)
Offhand: Tome of the Ice Lord (AV Exalted)
Wand: Wand with +21 (World Drop)
Gloves:Blood Guard's / Knight-Lieutenant's Silk Gloves (R7 PvP)
Waist:Stormpike Cloth Girdle (AV Honored)
Legs: General's/Marshal's Silk Leggings (R12 PvP)
Feet: Blood Guard's / Knight-Lieutenant's Silk Boots (R7 PVP)
Rings: Ring of Spell Power (MC Bosses)
Trinket 1: Talisman of Ephemeral Power (MC Bosses)
Trinket 2: Briarwood Reed (Jed Runewatcher, UBRS)
Honorable mentions
Legs: Skyshroud Leggings (Omokk, LBRS)
Wand: Wand of Biting Cold (AV Quest)
Weapon: Mind Carver (Prince Tortellini, DM West)
Back: Sapphiron Drape (Onyxia)
Ring: Eye of Orgrimmar / Songstone of Ironforge (Quest, BRD)
Ring: Maiden's Circle (World Drop)
Wand: Bonecreeper Stylus (Gandling, Scholo)
Additional notes
I don't play or always keep track of where the PvE server is right now, so if you notice this thread needs to be updated for a new patch or that I've missed out on items that should be in the game, please PM me and I will update it!
The only item that is interesting for a mage in raiding right now should be the Azuresong Mageblade (for when it becomes good), yay!
Since I've played on the PvP server since launch, I know for a fact that this gear setup combined with major mana + dark / demonic runes is far and away enough mana to sustain you on the longest fights available. If you are still going out of mana, it is not the fault of your gear, it is the fault of your guild for having shoddy boss kill times. Adjust accordingly, but don't blame me.
Best enchants currently in the game
7 int to wrists
4 stats to chest (or 100 mana to chest if that's your thing)
5 to all resistances to shoulders (Argent Dawn Exalted)
5 to all resistances to cloak
8 SP to legs/head (Arcanum of Focus)
Minor Speed Increase to Feet