UPDATE (17/07/2009): Chumby has just released software 1.7.1, and have fixed the codes for the Apple USB Ethernet Adapter. The following should no longer be required for software 1.7.1. It now works 'out of the box'. Since Chumby unleashed their new software 1.7, I've gotten a few emails...
UPDATE (01/07/2009): If you have updated your Chumby to software version 1.7, see this post to get it working instead. UPDATE (12/02/2009): There seems to be some kind of intermittent dropout happening with the wired connection using this adapter. A reboot will fix the problem, but it is annoying. Can't...