Hey I know what you mean, however I just linked pandora on the page as its a jukebox if you will, and just minimize it to keep tunes playing...not exactly what you wanted but a viable option.
Like I said in a post above, you'll want to look into using a popup window for it. Otherwise, there's no way around having the song restart.
I should mention that an integrated music player (with a playlist) is slated for development.
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It's all in the reflexes.