It's an intriguing idea, but one that I don't see working well. You are talking about creating something like USB, Firewire, or SCSI. All are very useful and support a varity of different devices, but the cost of designing an interface like what you describe for the empeg would be huge. It would involve design costs, and the cost of making the controller chip for this bus that decides where all this mixed data goes. So far, the empeg has little proprietary hardware. It uses a standard StrongARM chip, a standard audio chip, etc... Empeg mainly designed the way to connect these all together in a small package. They didn't reinvent a way to talk to a hard drive or serial device. For this reason, I don't see this idea going that far with empeg.

My empeg site is:http://24.236.3.131/empeg/