I have also previously documented the buggy ethernet of the RioCar. It works just fine when connected to a 10mb/s hub, but seems to fail regularly with many 10/100 hubs and switches. I now hardcode IP parameters for all of my empegs, but still note that the empeg is unable to communicate to the outside until at least two packets have been sent to it.
Probably just a buggy driver in the kernel -- maybe we should try pulling in a newer version of the ethernet code in hopes that the bug is fixed? Not likely I suppose.
Cheers