The thing is that, according to this site anyway, 360 only outsells ps3 by like 10-20k a week. With the price difference thats perfectly fine. Cutting the price would help PS3 outsell 360, but sonys wallet would be hit hard. And at the current level of sales I don't think its worth it for Sony to cut price right now. Makes more sense to wait for the holidays to roll around.
Time for hype