At E3 earlier this week, Microsoft unveiled a new 250GB Xbox 360. According to a report on Giant Bomb, there's also a secret 120GB version available.
Popping down to a local Best Buy to pick up one of the new consoles, Tested.com's Will Smith was charged $279 for his 360, not the $299 it should have been. Investigating, Smith says that his console was cheaper because of its 120GB hard drive, with the $250GB model going for $20 more.
This is the first anyone's heard of a new/different model than the $299 revealed at E3. Strange that Microsoft would a) go to the trouble of releasing a console that was only $20 cheaper, and b) not bother to tell anyone about it.
UPDATE - Giant Bomb have since updated their original account, with a statement that reads "After publishing this story, we were contacted by Microsoft representatives, who told us that the new Xbox 360 is only available in a 250GB configuration and that our story was in error."
There Are New 360s With 120 Gig Hard Drives [Giant Bomb]