It's similiar to the pink pogoplug but grey in colour and has built-in WiFi. Look here;

http://www.pogoplugged.com/blog/entry/14824/Pogoplug-Reveals-Pogoplug-PRO-Heads-to-Best-Buy-Near-You/

Remember, its not what life does to you, but what you do with what life does to you, that matters.

They gray one is a regular Pogoplug in gray color instead of Pink.
The all black one is the Pro. Standard Pogoplug with wireless all in Black.
The White one with the black 'sled' is the Pogoplug Biz.

Place Shifting Enthusiasts

The gray version is indeed identical to the pink Pogoplug, except for that it has a gray sled.