I was really upset by the fact that Sony reportedly signed the GTA series to an exclusive deal until 2004, when PS3 is reportedly going to begin production. I took it upon myself to check the source, and I found a few things. SCEA announced the "deal" at E3, but there has been no press release yet. So for all intents and purposes, it is not "official". I checked over at Take2 Games, and they too have not put out a press release announcing the agreement. They have announced that GTA:VC will be a PS2 exclusive, but they have not said anything about an agreement with Sony to keep GTA exclusive until 2004. Also, they have never officially cancelled GTA3, which was announced in February of 2001 and planned for a release this month.
Another important fact I came across was taht SCEA also spread a rumor at E3 that Metal Gear Solid Substance was to be a PS2 exclusive, but that was quickly shrugged off by the people that got to see Xbox demos and Konami's official announcement.
Sony announces one false rumor against the Xbox, then announces another deal that is yet to be confirmed by either party. The only thing that is set in stone is that GTA:VC will not be available on Xbox, but nothing has been said of GTA3 or any furter versions.
Lastly, I had some problems with my Xbox, so I called 18004MYXBOX, and to kill some time, I asked a rep about GTA3 coming to the Box. He told me it has been in development for over a year and has not officially been cancelled yet. He says that the Xbox team is not sure if the SCEA deal with Rockstar is true, but that he personally hopes it's not (of course). He says even if the rumor is true, GTA3 for Xbox will become a legal battle if Rockstar cancels it, because they have a contract calling for GTA3, Serious Sam, 4x4 Evo, Conflict: Desert Storm, State of Emergency, and Max Payne to come to the box. Also he says they are working on bringing Max Payne 2 to Xbox as an exclusive.
Of course I may be a dillusional GTA and Xbox fanatic clinging to my last hope, but everything that I have reported is true, so take it for what it's worth.