OK, official response.

"Q. What support is there for the Mac, or for Linux?"

"A. We do not currently support the Mac directly, however the Windows software will run under Virtual PC using an Ethernet connection to the car player. You may need access to a Windows PC for loading software updates onto the player, although we are working on a way to do this over Ethernet. We do hope to provide native Mac software in the future, but we cannot offer any specific time frame for this at the moment.

We supply a command line tool for Linux, currently as an i386 binary. It is intended that source code for this tool will be released in the near future to facilitate building for other hardware platforms."

Rob