Just to throw in my two cents on the whole "pads" discussion here.. the 4 off on their own (at least on the N800, don't know about the N810... assume they correlate to the ones that are circled in green) I would put heavy money on being header pins for USB. If you check them you'll find that when you put the tablet into USB Host mode, one of the pins goes 5V high just like it does on the USB connector. I got myself some pogo pins a while ago to test the theory but never got around to actually doing it...

As for the rest... well somebody mentioned serial/JTAG, which on the N800 again I know are part of the other group of pads that are exposed right beside the battery through a cutout in the sheilding, but I haven't investigated those myself...