http://nootropicdesign.com/ve/
This shield looks quite interesting - $33 assembled. It enables an Arduino to do video capture and overlay using the TVout library:
http://code.google.com/p/arduino-tvout/
I bet the Maple could do a lot more with it, since we have much more processing power available. It looks compatible from a hardware perspective.
For the most part the software looks compatible. There is some stuff in the TVout that is done in AVR assembly code, I think because C is not fast enough on the Arduino. I bet that could be ported to C.
Anyway I thought people here might be interested.
(via Hack A Day: http://hackaday.com/2011/03/24/video-experimenter-shield/)