I love me some Pandora -- it's an online music service that allows you to create virtual 'stations' based on your favorite artist or song, then allows you to refine that station by rating music up and down. They've created a wildly popular client for the iPhone, but Windows Mobile is still waiting. The good news: Pandora is working on a mobile client for their music service for Windows Mobile. The bad news: we could have written that exact sentence over two years ago, as this timeline at wmpoweruser makes clear.

It's not hopeless, though, as the CTO at Pandora, Tom Conrad, responded to the above with a well-written letter:

The good news is that we do have a team working on Windows Mobile versions of Pandora. Given my track record it’s probably best not to comment on the “when” but it’s certainly not a question of “if”.
At least for a small company like Pandora, the incredibly diverse mobile universe creates a real challenge with respect to where to place your limited resources. Without question the iPhone turned out to be a great bet for us. So far, the investment in feature phones has been a more modest success. We’re all optimistic that we’ll be able to find a iPhone-like success on Windows Mobile, but only time will tell.

In the meantime, there's always Last.FM.