how about an option to choose your location when you fire up Amarok and then it would load the music library for that location?  This way you could have a library for locally stored music on a laptop, but then could load a different library when you get to work for an external device, or load another library for a network share.

Amarok 2 supports multiple collections. This isn't fully implemented in 2.0 yet, but the architecture for it is there and works fine.

That sounds great.  I look forward to the new version!