Portal 2 - Why buy the PS3 version?

Many people who own a PC, 360 and PS3, or even just a PC and PS3 seem to be choosing the PS3 version over all else, why?

Is it perhaps the idea that one can buythe PS3 version, gain access to the PC version of the game and then sell it? Is that even possible or is the Steam version somehow tied to the disc?

And if you only want the PS3 disc to play the PC version, why bother with the PS3 version at all?

Second, is there any content available on PC that isn't available on consoles at release?

Sorry for all of these questions, I'm just contemplating which version to buy and I'm confuzzled as to why I shouldn't buy the 360 version as I normally buy my cross-platform games there...

Any response is appreciated!

Besides getting a free copy on PC when you purchase the PS3 version, you'll be able to play cross platform against PC owners.

We've got an official thread for the game.