Just setting up a page for 3.2.   Nothing much to see yet.   What we know so far:

• New epic 10- and 25-player raid dungeon with five encounters, with each encounter being unlocked one week at a time
• A more intuitive structure for harder encounters. This raid dungeon will have four different versions: 10-player, 25-player, 10-player Heroic, and 25-player Heroic, with each one using a separate lockout.
• Introduction of the Crusaders' Tribute! Each of the Heroic mode instances has a new tribute system that will limit players on the number of attempts they get in the Coliseum each week to present a greater challenge for the most battle-hardened heroes. Additional rewards can be earned depending on the number of attempts left in the tribute run each week when the final boss is defeated.
• New 5-player dungeon with three encounters that will include Champion’s Seals as each one is defeated
• New tier of armor and weapons that are modeled with Alliance- or Horde-specific themes

5 man:

From datamining and speculation from achievements, you're likely gonna be facing some champions of the other faction and Argent Crusade tournament ones, and The Black Knight.

Here's some datamined stuff from Argent Confessor Paletress.   The fight apparently has memory spells, which summons bosses from the past into the fight.  It is unknown whether it'd simply be a cutscene, or you have to fight a 5 man level 80 version of them.    Anyways, here are the datamined memories.

Wrath of the Lich King

• Raid Bosses
  • Algalon the Observer
  • General Vezax
  • Heigan the Unclean
  • Ignis the Furnace Master
• Dungeon Bosses
  • Cyanigosa
  • Eck the Ferocious
  • Ingvar the Plunderer

The Burning Crusade

• Raid Bosses
  • Archimonde
  • Entropius (M'uru)
  • Gruul the Dragonkiller
  • Illidan Stormrage
  • Lady Vashj
  • Prince Malchezaar
• Dungeon Bosses
  • Priestess Delrissa
  • Warlord Kalithresh

Classic WoW

• Raid Bosses
  • Chromaggus
  • Emperor Vek'nilash
  • Hakkar
  • Lucifron
  • Onyxia
  • Thunderaan
• Dungeon Bosses / Quest Targets
  • Edwin VanCleef
  • Herod
  • Hogger
  • Mutanus the Devourer

10/25 Man:

Right now there's looking to be 8 bosses in the Coliseum, which includes going under it into some Nerubian caves.

Gormok the Impaler

Dreadscale

Lord Jaraxxus

Fjola Lightbane

Acidmaw

Icehowl

Eydis Darkbane

Lightbane and Darkbane is probably the same fight, ala Twin Emps, Eredar Twins type thing.

Also the final boss is looking to be...  Anub'Arak.

Not confirmed yet, but could be similar to the frost cryptlords:  http://static.mmo-champion.com/mmoc/images/news/2009/june/anubarak_not_c...