I and I think a few other people have been trying to find a good way to interface 8x8 common cathode rgb led matrixes with the arduino.
I made a post on my blog about the options currently available. See next post.
but I was wondering what everybody else might think about this situation. My current plan is to wait and see what the Seeed Studio Rainbowduino looks like when released. From what I can tell, the SparkFun serial connected matrix seems like it would be by far the easiest to use, as it has libraries implemented for it already... However they will not sell me the driver separately from the matrix, and I already have a matrix! It also is a bit expensive IMHO.
Thoughts? I am not quite ready to build my own driver yet, I don't think my soldering skills are good enough.