FYI for any who want a portable Chumby 8.
I like to be able to carry my C1 around and always wanted to do the same with my C8. Some time ago I got hold of an Infolithium NP-F570 and with the promising developements in the Chumbysphere, I was motivated to do something.

The battery puts out 7.2 volts and this must be dropped down to 5v  for the C8. I used a Texas Instruments PTH08080WAH adjustable switching regulator. It is very easy to use and extremely efficient.

I couldn't work out how to upload images so I can't show the circuit or build pictures. I used the circuit given in the TI application note. The only additional components are a 220uf capacitor and 270ohm resistor.
The C8 seems to draw about 940ma and with a fully charged battery I get about 2.5 hours. Great!
My build is not that pretty but it works.
It would still be useful with a smaller lithium battery- the good bit is the regulator.
Hope this is of interest.