MS for the most part made sure that the PS3 would one day pass it when it refused to drop the price by $100 earlier this year, when it chose to ignore the 360's hardware defects, and when it failed to cover more genres other than shooters, racing/driving sims, and sports.
The 360 does decently in N. America, but it does poorly in Europe and downright horribly in Japan. The fact that the PS3 is still outselling it in those regions despite the price difference and less software should ring a bell. The PS3 appears to have the bigger and more diverse lineup in 2008. The 360 has some anticipated titles coming, but it's still a pretty one-dimensional showing. There still isn't a prominent platformer, JRPG, offstyle racer, or action/adventure game. The software of the 360 exclusively targets older american males, which is why it's only managed to do well in NA. The 360's hardware sales have actually decreased month over month throughout the year despite more software. They even decreased the month that Forza 2 was released.
The PS3 will probably be at $300 by next Christmas, and while the 360 could be at $199, it still won't matter because they'll both be at mass market price point(the $299 PS1 and PS2 outsold the $199 N64 and Gamecube) and the 360 doesn't seem to have anything to answer FFXIII and GT5.
That being said, 2008 is a bit too early. I'd say the PS3 passes it some time in 2009.
Consoles owned: Saturn, Dreamcast, PS1, PS2, PSP, DS, PS3