Well there is some interesting info out there now... Take a look at this.
The hardware specs of the xbox 360 has now been confirmed!
It was written and printed in the latest danish paper Gamereactor, and here is what it says:
3xIBM PowerPC 3.2GHz
ATI Graphics with 10mb embedded DRAM
500 millions polygons/sec
48 billions shaders/sec
512mb GDDR3 RAM
20gb HDD
12x DVD Dual Layer
Mem card 64mb
up to 4 wireless controllers
3xusb ports (1 on back 2 on front)
Xbox-Live integrated
Ethernet
Wi-Fi 802.11 ready
cam ready (up to 1280pixels)
reads: DVD-video, DVD-rom, DVD-R/RW, DVD+R/RW, CD-DA, CD-ROM, CD-R/RW, WMA-CD, MP3-CD, JPEG Photo-CD
Can stream from Media Player Windows (PC), digitalcamera (then send pics over live)
Supports: 16:9, 720p, 1080i, 5.1 Digital, personal soundtracks...
Thats about it, and everything may not be 100% correctly translated but it is something...
For more info and full scans from Gamereactor read here:
all of it