Reading the Slashdot thread on networking via electrical outlets [1] there was mention of the Intelogis PassPort Powerline Adaptor [2] which allows data transfer over existing electrical wiring and apparently available at CompUSA [3] and other like stores. It's a bit late to head over to CompUSA, but tomarrow I'll see if I can pick it up if it's cheap enough. At 300kbps it won't be fast, but it's fast enough for what I want to use it for.
[1] http://slashdot.org/article.pl?sid=00/06/07/1328233&mode=thread