So after much thought (and accidentally blowing away the filesystem on the sheeva), I'll be going a slightly direction with my setup.
I knew upfront that it was less-than-optimal because I would still have to use two boxes. Yet I couldn't find hardware that would perform the media functions of a carpc (which i currently used a zotac ION to accomplish) *and* have the low power requirements of the sheeva. I was thinking on going with a beagleboard. But with only 128 RAM and 256mb Flash, I was discouraged... that's not a lot to work with. The gumstix board has twice as much RAM, but that still isn't a lot to work with.
Times have changed... A user on the Openice forum pointed me to this device which he was trying to run nGhost on:
This is 720MHz, 512mb RAM and Flash! It's the bigger, stronger, faster brother of the beagleboard and still only consumes ~2W! That's less than the sheeva! It also does OpenGL ES 2.0 and can do 720p video without much effort.
So lets do a little math:
zotac ION $180
power supply $60
Total wattage: 6-30W+
Total Cost: $629
Total wattage: 2-3W max (not including touchscreen)
Total cost: $480
It's also worth noting that ARM processors can go into idle states at 0MHz and draw only 15mW or so. This is about what your PC would be drawing when sleeping only this system isn't sleeping!
So I save money, energy, and trunk space by going with the igepv2.
PS. the company that makes this will be coming out with an expansion board with GSM/GPRS, 3 pin CAN interface, and video inputs in Q3 2010.