The site has been up for awhile, so I don't know how new it is. I've heard it's coming to an Apple store soon a number of times since before Christmas.
While I do agree that's it cool-looking, I went out and bought a different FM transceiver, the Akron Soundfeeder.
It uses 2 AAA batteries, lasts for a long time and works easily enough. Sometimes there's a little bit of interference when radio station on the lower end of the spectrum bleed over to the setting I have it, but that's rare.
In fact, when I'm out, I often use it to broadcast to my Nokia's built-in radio so I can listen to music and take a call if one comes in. It would be nice if newer iPods had this, but then I'd have to go and buy one...