Colin just updated his web page:
I just finished my RS-232 converter, and photo-frame hardware mods. I followed (mostly) Colin's HOWTO to get the intial boot loader flashed into the frame. Haven't yet built a kernel...
Note for PeteC: you'll have to build the RS-232 converter and do hardware mods (both easy - took me about .5 day), in order to re-flash the frame's built-in software. Hope that doesn't prove too much of a hurdle!