most people will buy it for the pstriple

Of course it has somes effects, because the userbase difference between PS3 and X360 in the USA is quite big.

Valve is smarter than us. Idea behind this is very simple. PC version is Cheaper than the PS3 version. You are unlikely to buy the same game twice. Rather than seeing PC / PS3 owner get the cheaper and probably superior PC version, they make sure to produce a deal and looks too good on paper for gamer to pass and force them to purchase the more expensive version. The end result is an increase in revenue AND additional exposure in a market they've never penetrated. They only thing I'm puzzling over is how they are going to stop PS3 owners from buying this game and then selling the PS3 copy while keeping their steam copy.

My friend is strictly a PC gamers although he also has a PS3 for exlusives. He is getting the PS3 version since he still gets the PC version (which is the one he is gonna play) and he can play Co-op with his girlfriend / borrow it to his nephew. Its a good deal and i think a lot of PC PS3 owners is gonna get this version, because of this. So i think it should affect sales a lot and i think it will outsell the 360 version by quite a lot everywhere except in America.

I hope my laptop can run portal 2 since il be getting the ps3 version and would like to try it out

Um, I guess you haven't heard about what the PS3 version will do that the 360 will not. 

Microsoft REQUIRES that companies charge for DLC, whereas the PS3 version doesn't have said requirement.

Microsoft REQUIRES any patches to be approved before going live, so any patches for 360 will come through MUCH LATER than the PS3/PC/Mac versions.

Steamworks allows you to play cross platform with PC users, and the PC user community is generally filled with older, smarter, more mature players as opposed to the idiot 14 year olds on XBL.

Also, Steamworks allows PS3 users to download user made maps and a whole lot of user generated content.

I own all three consoles and a Mac I game on, and the PS3 version is CLEARLY superior.

I bought PC only, dont need physical media. And the PC version will outsell both console version. It will happen no matter how much people think it won't. Thats how Steam works.