Taken from the Press release found at Vivendi’s Site
December 2, 2007 (Santa Monica, Calif. and Paris, France) – Activision, Inc. (NASDAQ:ATVI) and Vivendi (Euronext Paris: VIV) today announced that they have signed a definitive agreement to combine Vivendi Games, Vivendi’s interactive entertainment business — which includes Blizzard Entertainment’s World of Warcraft®, the world’s #1 multi-player online role-playing game franchise — with Activision, creating the world’s largest pure-play online and console game publisher. The new company, Activision Blizzard, is expected to have approximately $3.8 billion in pro forma combined calendar 2007 revenues and the highest operating margins of any major third-party video game publisher. On closing of the transaction, Activision will be renamed Activision Blizzard and will continue to operate as a public company traded on NASDAQ under the ticker ATVI.
This will make them the largest gaming company in existence, assuming all the regulatory necessities go through fine. The expected date for the merger to be complete is reported to be mid 2008, but I doubt we will see anything significant for a time to come.
EDIT: At least Blizzard have stated they have no plans to port WoW to the Console