MacRumors.com

With previous rumors already pointing to tuesday or wednesday for a release of new powermacs, Amazon.com appears to have let the cat out of the bag early by posting a listing for a Dual 2.7 Ghz PowerMac.

Apple's online store and hardware listing pages remain unchanged as of yet.

Amazon specs include:
Mac OS X10.4, code named Tiger
Dual 2.7 GHz PowerPC G5 processors
512 MB of DDR SDRAM
250 GB hard drive
16x Dual Layer SuperDrive (CD/DVD+RW)

[Update]
Amazon also has listed pages for the new dual 2.0 Ghz & dual 2.3 Ghz machines with the following specs:

Mac OS X10.4, code named Tiger
Dual 2.0 GHz PowerPC G5 processors
512 MB of DDR SDRAM
160 GB hard drive
16x Dual Layer SuperDrive (CD/DVD+RW)

Mac OS X10.4, code named Tiger
Dual 2.3 GHz PowerPC G5 processors
512 MB of DDR SDRAM
250 GB hard drive
16x Dual Layer SuperDrive (CD/DVD+RW)

Update: Amazon has removed the products and replaced them with "Coming Soon" placeholders.