Did some experimenting with bluetooth and bandwidth, by creating a BT server that receives 40-byte packets and replies with 40-byte packets, similar to what the Gumstix is doing on my biped, but without any actual processing. My hope was to get more bandwidth by using a raw bluetooth socket instead of building on top of the bluetooth serial port profile, but alas, the SPP overhead is apparently negligible.
I can up the packets to 80 bytes and still get 60 frames per second between my desktop and my laptop, but on the gumstix I am stuck at about 15 fps even with the raw socket approach.
On a related note, one of my Gumstix is booting Windows CE now, so the above testing was all done with C#. Unfortunately, debugging requires either USB or ethernet and my biped has room for neither, so I need to figure out a way around that (ActiveSync over bluetooth?) before I reflash the Gumstix in the biped to boot CE as well.
Currently the CE-on-Gumstix stuff is only usable by people with Platform Builder (Microsoft's CE development suite), which is pretty expensive. But with any luck, that will change in the not-too-distant future.