There are three things that we can all rely on. Death, taxes, and that each and every Assassin's Creed III game will be delayed on PC.
The odd thing is is that every time one's been announced, we're told with incredible forcefulness that - this time - the game will release simultaneously on all platforms. Sometimes it's with a certain knowing smile, admitting that this is a bit of an issue; other times, there's a sense that Ubisoft has absolutely worked out how the PC works, and there's no doubt the game could possibly slip.
Which only makes me think, on top of certain DRM issues, that Ubisoft's powers that be simply do not get the PC.
Regardless, if you're a fan of the series, and you insist on playing it on PC, you'll be waiting until November 2012 to play the game. Or you could just snap and get it when it comes out on console at the end of October.