Normally you'd expect one white wire and one black wire. I had two brown wires and two black wires--- and one brown had been connected to one black. After significant trial-and-error (i.e., blowing the circuit breaker a few times by flipping the switch to 'off'.), a little bit of reasoning, and the application of a voltmeter, I managed to figure out what was going on. One pair of black and brown went to the house circuit; the other pair went to the wall switch. So instead of two connections in the ceiling (hooking the load between two power lines) there needed to be three: putting the load in series with the switch, and hooking the switch back into the house circuit.
(Last weekend I replaced two fluorescent ballasts. It's lighting central over here.)
I'm also experimenting with compact fluorescents in my office. They're very... blue. Unfortunately the pictures I took mainly demonstrate that my office is blue and the master bedroom is yellow (with yellow-hued lighting.)
One of the CFL bulbs has flickered every once in a while. But, if I can make the switch my office should be significantly less warm during the summer months--- multiple computers tend to heat up my work space.
Dang it, I want LEDs.