I do. On GC Super Smash Brothers did extremely well, almost half of GTA SA, with a much smaller installed base. Now, Wii is within 10% of having a bigger market share tahn 360/PS3 combined, and with typical long Nintendo legs and a broad appeal to gamers (a LOT of people are waiting to buy a Wii for this one), you might just have a GTA-killer saleswise.

....grand theft auo 4 will probly destroy....well....everything....its freaking grand theft auto,even there stupid side stories sold like 4 million and on the psp each

Since we're only talking about the PS3, I'd have to say Gran Turismo.
The only games on the PS2 that sold more were the Grand Theft Auto series, and this time GTA is split between 2 platforms, with the lion's share most likely going to the 360 due to the much larger userbase.
If you look at the other platforms, I'd say SSBB will sell best on Wii and GTA4 will be the top seller on 360.
I believe that SSBB will be the year's best seller due to GTA4 having a split userbase, and will probably outsell the two versions put together. GTA: San Andreas sold 17 million (combined PS2 and Xbox) to SSBM's 6.5 million, on a user base many times larger than the Gamecube's. Super Smash Bros. Melee sold 1/3 the amount on a userbase that was roughly 6x larger.
If Brawl has anywhere near the attach rate that Melee had, or even if it manages only about 60% of it, then it will outsell GTA4 on both platforms combined.

GTAIV if you count PS3 and X360 sales together.

everyone knows that the top selling game in 08 is going to be Wiisports. :P

WTH... I'm in the Sony forum? I must have taken a wrong turn at Albuquerque. now how am I gonna get to Pismo Beach?

Don't mind me then, carry on. Oh, and I'm going for Little Big Planet. It's got the casual pull that's going to give legs to the game, and may actually be able to break PS3 into being viewed as a console for casual gamers as well. 

combined sales of GTA4 from the 360 and ps3 will crush all. But if it's just 360 sales or ps3 sales then GT5 will probably be bigger.

I hadn't thought of it like that... but you know what, I'm not going to think of it like that. GT is still my pick for top selling PS3 game that's released in 08.

In case you didn't notice, you are posting in the Sony forum and this poll is PS3 specific.

Which means anyone that voted for GTA to sell better than GT5 needs to look at sales records. 360 will take some of the GTA sales and GT sells almost as much as GTA on average.

no it wouldn't, i hate to say it but it would just be wii fit.