After the release of GTA IV for the consoles, I went to do some searching around the internet for a possible PC version of the game. After weeks for searching, I found this website that indicates a possible release date for the PC version, along with evidence to prove it, even though I haven't actually seen it.
According to this website, the PC version's release date was found in the manual of the Xbox 360 version of GTA IV as December 13, 2008. Unless this is a typo or something thats made to mislead people, then it is possible that this release date is real, even though no release date has been confirmed by Rockstar Games by one of their representitives.
You people think about it, even if this misleading information, Rockstar will make a PC version of this game. They know that not everybody has a PS3 or Xbox 360, so that would not be stupid to corner themselves and not market the game to pc owners.
GTA IV will be on PC, its all about when it will, assuming the link is giving fake information.