AFAIK, the (newer) standalone players are intended for paid accounts only (I run Pandora One using Adobe AIR on my desktop, which uses roughly 10% of my CPU). I haven't tried pianobar yet, but hope to soon (maybe try creating a plasmoid to control it, if possible). Barring library issues, I'm hoping it will run on the N900. It would be really nice to have one or more such backends controlled through a unified interface.