Another neat hack from Fabrice Bellard, the guy behind FFMPEG and QEMU. Granted, it's not technically "broadcasting" the signal because signal strength is so low, but it's a neat trick.
Being that this page is from 2005 (almost exactly 4 years ago!) and the source is still not available, I would say that it is a neat trick, but also difficult to reproduce.
Fabrice is one of the greatest living hackers out there.