Remedy's shot down talk of Alan Wake coming out in September, running the old "when it's done" line on the game's official forum.
The game has been off the radar for some time now, having being in the news the last time in late January, when a bogus interview pinned it for a GDC showing which, obviously, didn't happen.
Nothing official's been seen on the Microsoft horror adventure for many moons. In fact, the last shots released were at X06 in Barcelona in September 2006.
Looks like you're going to be waiting a while yet.