BlizzCon attendees are now able to copy up to four level 70 characters to an event realm. Attendees will have the
chance to experience new content at the event using their own level 70 characters or a pre-made character. Those
wishing to make copies may do so at the character copy page, which will be available until the end of
BlizzCon on August 4, 2007.
Original post by World of Warcraft Community Site