I just saw a device called SitePlayer. It seems you may be able to add a limited ammount of ethernet connectivity (ie. Displayserver) to an MK1 with this device.

WOW! At only $100 for the Developer kit and $30 for the modules, I'd gladly help fund someone to research integrating this into a Mk1. This could put the IrDA interface to some good use in the Mk1's - those without BlueTooth, anyway .

But since its interface is serial, what advantage would you get over just using the Mk1's serial port?

this one has some other nice features:
http://www.ibutton.com/TINI/

Probably little in the way of speed, unless it supports 230K and your PC's serial port doesn't. It's made for devices, and Linux can do in software anything this can do in firmware. But adding an ethernet port for $50 (parts&labor) would be worth it to lots of us.