from network magazine

"The laws of physics say that point-to-point radio links are easy to set up: Just point two transceivers at each other and ensure that there's a line of sight between them. But the laws of man are different: Thanks to interference issues, high-bandwidth wireless systems usually require a costly and difficult-to-obtain license, ruling them out in most private networks.

One alternative is to use light. You don't need a license to set up a pair of flashlights or laser guns, and a single beam of light offers more bandwidth than the entire radio spectrum."

An email from the seattlewireless list points to the Ronja Project