Okay, thanks to some outside help (Zimmer!), I've gotten music from GrooveShark to play without needing Flash installed. Hooray! That means that a Linux version (and maybe an OS/X version) should be released in a week or two. Also, after that you might see things like a pause button, and have the ability to seek within the song. Hooray!

Update:
My development version is coming along quite nicely. No more 'yellow-can't-figure-out-the-time-of-song' problems. Add to that super quick playing, i.e. the wait time before playing a song is pretty much gone. ...maybe a new version for Windows users as early as tomorrow.
Update2:
Woot! Hacked up a Linux version and it works, kind of.
Update 3:
Windows release imminent.