i just ordered one of these Maxxon brake lights:
Wireless Bicycle Brake Light for Mountain Bikes, City Bike Carriers, and Dynamo Bicycles
an inertia sensored, Nintendo/Wii technology, 2007 Taiwan Innovative Prize Winner, burble burble burble...
looks like a really cool tail/brakelight with no external wires whatsoever. looks small enough to hide under my seat, or in the duck-tail of my fender.
i don't want wires or sensors or any extra crap anywhere on my bike, and since i ride in the road with traffic at 40+, i figured this would be the hot set-up.
for the front, i dunno, i gotta make something...
(edit: it was only $30 total on ebay, not the 50 on the website...)