Don't know if you saw my current project that I called matriduino.
http://melka.one.free.fr/blog/?p=145
What I want to do is attach an ATmega168 on the bottom side of a PCB, and an 8x8 LED Matrix on the top side. I have a few more chips with it (TLC5940, ULN...) to control the thing.
Maybe we could do the same with this baby : just have a 7805, ATmega168, XTAL and Stuff, program it via ICSP and have a connector for I2C / Serial communication. This way, the board + matrix can be standalone or controlled via a master chip using the I2C connection.
The matriduino is bit more complex, as I want to have PWM control over each leds, "high power" via 12V supply for the leds, etc... but the idea is the same.
But this can be expensive and not worth trying to do, as Sparkfun already have done it...