More games have been pushed back to 2008. First in line was the Ubisoft press release that shows their fall/holiday line-up of games. Also IGN.com has done a Q&A with Pandemic Studios President Josh Resnick, which states that Mercenaries 2 will also be pushed for the Q1 2008.
Ubisoft has Assassin's Creed listed for their fall/holiday 2007 line-up, but only the Xbox 360 and PS3 versions. The PC version of the game will have to wait until the Q1 of 2008. No details were given on why it got delayed, so your guess is as good as ours.
IGN.com has done a Q&A with Pandemic Studios President Josh Resnick, and managed to confirm that Mercenaries 2 is indeed delayed until 2008. The reason for this delay is the most common one, "we would rather make sure that every corner of our vast, open-world, highly explosive gameplay is completely polished. We owe that to Mercenaries fans."
Lets just hope that these titles are the last to be delayed or this holiday season won't be that good for the gaming community.