I just picked one up at Walmart for $5.
First impressions:
* It has 7 games (Ms. Pac, New Rally X, Bosconian, Mappy, Galaga, Pole Position and Xevious), the wired version has only 5 (New Rally X and Bosconian were not included)
* The version of Bosconian that is included is improved upon the version that was included in the Pac Man unit (it has the voice synthesis now and of course it has an 8 way joystick instead of the 4 way on the Pac Man unit)
* Saved games don't appear to allow initials