with the CF slot in the Zaurus, which allowed wifi, bluetooth, POTS modem, gprs/gsm, ethernet, CF and microdrive, I/O cards etc, the Zaurus would probably never have become such a cult classic. It's clear the zaurus developers never anticipated that the CF slot would give their product such versatility!
Not only that, more recent models had a mini-A usb socket so you could plug in digital cameras, keyboards etc without needing funky adaptors!

if the tablet isn't going to gain a CF slot, which is unlikely, at the very least fit a useful USB socket with sufficient power to drive a 3g usb modem, PLEASE. Otherwise, as people have asked innumerably, a docking connector would be ideal... model it on single lane PCIe or something, add usb pass through and video pass through!
At present the tablet is very much an appliance, but it could be so much more.