Seems as if MS is trying deal with the PS3 recent sale hike due to their price drop with their own.
I doubt that's the reason for the price cut, as the sales numbers aren't out yet. The June numbers came out and the 360 outsold the PS3 198,000 to 98,000 (this is from memory, i may be off by a little). It was a 2:1 margin. The Wii outsold them both. I think the PSP outsold the PS3 too.
Undoubtedly, the PS3 sold more briskly after the price drop. I bought one about a week after the drop, but there was still ample supply at the EBgames i went to, and no Wii's to be found.