This may be way off base with what is trying to be acheived, and not as neat... But how about a USB<>Ethernet converter?

Something like an SMC
:-
http://www.smc.com/index.cfm?action=products_show_datasheet&productCode=SMC2206USB/ETH

http://www.smc.com/index.cfm?action=products_show_datasheet&productCode=SMC2208USB/ETH

http://www.smc.com/drivers_downloads/library/SMC2208_DS.pdf

They are getting small and compact... US$30 from outpost.com

http://shop1.outpost.com/product/3237311

SMC do win and linux drivers for it. Not totally platform independant, but not too shabby...

I use a older larger version for my ADSL, and it works well...

I know some are also using a combo wireless media converter (into the empeg/rio ethernet port whilst in the car sled), 802.11 card and wireless gateway , to synch while the player is still in the garage, and also optionally scare the crap out of someone walking by the office when it's in the carpark, and you turn it on and blast an appropriate tune - as I do works well... similar idea....

Thoughts ?

Cheers,

Kieran
OZ