I believe problems with the Pandora Widget caused when you moved Pandora to the SD card have been fixed. When I updated to Froyo and moved apps to the SD card, it broke my Pandora widget, and I've read that this was an unfortunate side-effect of having the app installed on the SD card. But when Pandora updated, I tried the widget, and it appears to be working, even though Pandora is on the SD card! (I checked in "manage applications" to be sure I hadn't moved it onto the phone and forgotten about it).
It's possible this was fixed in an earlier Pandora update and I'm just now discovering it, but I don't think so. Of course, there are probably other fixes or enhancements in the latest update, but I don't know what else they are.