For those of you holding back on buying Cataclysm, Blizzard is offering a free 10-day trial of the expansion. All you need is to have your account upgraded with all the previous expansions and a level 78 character. Keep in mind you'll need a level 80 character to actually do any of the quests in the brand new zones. For more information, refer to their FAQ: of note, any characters you make will count towards your total character limit, any Worgen or Goblins you make will become locked and unusable after the trial expires (though accessible again if you upgrade), and any non-combat pets you acquire you will be able to keep.