I finished the work on the driver some time ago, but had a bunch of issues with Eclipse, WinAVR and the avr-eclipse plugin. To get things to work reasonably well, I had to reinstall Eclipse. I'm now running Eclipse Indigo with the C/C++ Development Tooling (CDT) and the avr-eclipse plugin. I've also added the subclipse plugin and moved the development projects into Subversion.
There are a few drivers for the MAX7219 and MAX7221 out there on the 'net. I've seen two drawbacks. One is the GPL and the other is some general design philosophy. Since the MAX72xx are character displays, the drivers seem to be oriented towards that, or towards driving dot-matrix displays. The latter is closer to what we want, but I'm still not satisified with it.