Blizzard Frontman Bill Roper confirmed us yesterday during an event at Vivendi Universal that the forthcoming Patch has the character of a second expansion set. Apparently all seem to have changed, only the character classes and the acts are the same. From the Unique Item to the character Skills up to the monster-AI the Californian manufacturer changed radically everything, that one only can change radically. A complete test course of the patch lasts about three weeks and the actual Bugfixing makes many many of such test courses necessarily. Especially: the problem of the "duped" (illegally reproduced) items.
Yes, I know the wording is weird, but it was translated from a german site, plus aside from this, they said it will most likely be finished at E3 in may.