So I've been thinking about this for about a year now. Localtalk (serial) used RS-48 something, (I think RS-488 but ive been corrected before). Anyway, there's a spec called FDTI that supposedly communicates using the same protocol. These devices are available to convert RS-232 to localtalk. I am imagining something like a embedded Intel Atom machine, or perhaps some of the AMD Geode junk I have lying around (which includes a built-in RS-488 whatever port) to pick up signals from the serial side of the mac. There would be a C program listening to these serial messages (which I have not seen yet) and construct IP packets which contain the IP version of these messages (which is easy using Wireshark). The layout is a bit cryptic from the TCP/IP side of things, however the messages appear to be standard.

Anyone interested in helping??