This is the best looking mouse I've ever seen.
What's so special about this mouse? Well, besides functioning as a normal mouse, it can also be motion controlled, hence the name "Air". It uses accelerometers like the Wii remote. It's designed for home theaters where you may not have a surface to use it on.
It's also really hard to photograph without proper lighting. There are better pictures out there.
The buttons are also backlit. The scroll bar is touch sensitive. There are many mice with touch sensitive scroll bars now, like Apple's Magic Mouse, I think Microsoft's Arc Mouse, and Logitech has a few touch mice too. I particularly like the inertial scrolling in the mouse. Since there's no physical feedback to a touch scroll bar, there's a small speaker that makes clicking noises when you use it. Some people might find it irritating, I don't because it's very soft. If you flick it hard, the clicking noises continue, like a wheel. At that time, I think only the MX Revolution had inertial scrolling. That was interesting, they did it by using an extra heavy wheel, and the mouse had a clutch that would release the wheel if you spun it hard enough, allowing it to spin freely.
In accordance with my protecting all my devices as much as possible, I stuck PTFE tape on the mouse feet to extend their life. Oh it uses an infrared (848 nm) laser for desk tracking.
It even comes with a cleaning cloth with its name on it, showing Logitech paid more attention to the design of this mouse. Some other products that came with cleaning cloths: MacBooks, iPod Touch (but not iPhone)
It charges on a dock. You can see the charging contacts on the bottom of the mouse in one of the pictures above.
I don't think they make it anymore. What a pity. Some problems with it were: the motion tracking wasn't very good, it tended to drift (that's probably why the Wii needs a sensor bar), and my main issue is the battery life is very short (20 hours!), especially when there are mice with battery life in years now.
I bought it for AUD139 in 2008, which is surprisingly cheap. It was selling for >$200 SGD, and even Amazon is more expensive.