The full patch notes for World of Warcraft version 4.3 Hour of Twilight have gone up on Blizzard's blog.
The patch includes a whole host of tweaks, fixes and new additions such as new dungeons, raids and items.
New features include the new Raid Finder which "allows players to quickly and easily form a pick-up raid for a specially tuned version of the current tier of endgame content"; Transmogrification which "allows players to customize their gear" by "copying the appearance of one magical item onto another"; and Void Storage so that "players will now have access to a new 'deep storage' system, allowing characters to free bag space by setting aside coveted gear."
There's also the Darkmoon Faire which features "new quests, shows, games, recipes, toys, balloons, souvenirs, snacks, beverages, achievements, and titles."
All in all, there's plenty changed. For the full patch notes, check them out over at Blizzard's website here. Blizzard also released a video which shows off some big monsters. Have a look: