In a statement, Ubisoft said, "[The launch of GRAW 2] will take the place of Assassin's Creed and Brothers In Arms Hell's Highway, which will now strengthen fiscal year 2007-08," which runs from April 2007 through March 2008.
That info implies that the highly anticipated Assassin's Creed was planned for an early 2007 release, even though it was always tagged with a "TBA" release date. Hell's Highway was expected to be released in the first quarter of 2007. Both games are in development for the PlayStation 3, Xbox 360, and PC.