It is looking like the fan petition to get Dark Souls on PC may have done the trick, according to recent information.
There are a few things that make it seem likely. First of all, the Facebook page for the game tells players that an announcement is coming, and that people can find out what it is by 'Liking' the page and sharing it with friends, an incresingly common way for companies to pick up loads of followers and then give out some info that they probably would have been giving out anyway.
In addition to that, an Australian magazine called PC PowerPlay has a teaser for their next issue that features the Dead Souls 'You Died' screen. It seems unlikely that something that specific could be a coincidence, or for some other game, so this one is looking like a lock.
So, any PC players out there looking forward to playing Dark Souls? Any Vista users should be well acquainted with the frustration that the game provides, so maybe they have a leg up on the console crowd.