Mustafa Taleb has released his unofficial Pandora app for Windows Phone, dubbed MetroRadio, into marketplace. Â The app appears to work pretty well, including being able to thumbs up and down a song, and crucially works even internationally.
The app also supports background playback, and has a pretty reasonable UI.
The app is free and ad supported, and I suspect will shortly be pulled from Marketplace by Pandora, so rush over and get it while you can ASAP.
Get it from Marketplace here.