Yes, Remedy's "psychological action thriller" remains in development after over four years. In fact, Microsoft revealed last month that Alan Wake is on track to launch some time next spring. But there's a twist: Remedy may target the Xbox 360 first and follow up with a PC version some time after that.
I'm a PC gamer at heart (have a Core i7, Radeon 4890, 5.1 audio setup at home) so I do appreciate your concerns.
Unfortunately all I can say at this point is that we're focusing all our efforts on the 360 version and will be making comments in regards to the PC at a later in time.
Remedy seemed to hype up the PC version much more in the past. Back in September 2006, the Finnish development studio went so far as to demonstrate Alan Wake at Intel's Developer Forum, presenting it as a poster child for the benefits of quad-core processors in PC games.