I just received a notification that my PCBs are on their way to my desk. I made prototype PCBs to evaluate some parts, like NXP's SGTL5000 audio CODEC. I was originally planning on using TI's TLV320AIC3106 in BGA package, but the ball pitch is so small that you would need a costly PCB service with very good specs.
I haven't started working on the battery-oriented aspects at the moment. I'd like to use an integrated solution like Linear's LTC3557 Li-Ion charger+Buck solution.