iPhone multiple library sync

It would be great if the iPhone app could sync to multiple libraries. I have my music on a central 'server' (Mac mini home theatre) but my books on my MacBook as they get updated most frequently.

It would therefore be really handy to be able to sync to both libraries on my iPhone (or of course be able to syn the 2 libraries)

That being said overall the app is excellent, just need to get past this stumbling block!