Thanks to a tip off from a forumite from Half-Life2.net I was pointed in the direction of GameRush which in turn linked me to German retailer CityDisc which lists a PC version of GTA IV for a November 30th release.

Considering previous GTA games have taken between 6 and 8 months to arrive onto the PC this does seem a plausable release date. It is also a date that sits well with the holiday game rush.

I am going to get in touch with RockStar to try to get some clarification on this.