There's nothing really enticing me to buy a PS3 at the moment, no matter how much I want to play MGS4. However, there is an interesting game coming out for it called LittleBigPlanet, which is supposed to be a cooperative platform game. You can also create your own levels or download custom levels from online. The game looks GREAT, not to mention adorable. Here's a clip from the recent Game Developer's Conference that demonstrates creating a level:

A trial version of LittleBigPlanet is expected to arrive on the PlayStation Network this fall, with the full version following in early 2008.