Solar sails.

Long-used staples of science fiction, solar sails are about to be unfurled for real. Funded in part by the Planetary Society and part by a movie studio connected to Carl Sagan, the Cosmos 1 project will launch a satellite tomorrow which will test the solar sail concept. (NASA is working on a similar project to launch after 2010.)

It won't quite be the space-sailboat races from the Moon to Venus that I recall reading about in the '60s, but it's a start.