The 60GB Xbox 360 just popped up on Amazon for pre-order. They've got it listed for $349.99 (duh), shipping out Aug. 4. The price cut on the 20GB Xbox 360 is in full effect, too. [Amazon, Thanks Chris!]
If you're deciding between Xbox360 or PS3, go with PS3. I own both (and the Wii), and the Xbox360 has been nothing but headaches. Broke 3 times, and now is out of warranty and broken again. Don't believe the 5 year warranty or whatever has been reported in the news, the warranty that Microsoft extended was only for the red-light problem. There are a lot of other issues with the Xbox360, most of which are only covered with a 1-year warranty. Google and see how many people are having problems with the Xbox360, it's a faulty product. Microsoft quoted me $100 to fix it, and after 1 hour of arguing they dropped the price to $50... go with PS3 people, it plays blu-ray and does 1080p.