They do not work.
I tried Wal-mart bulb made by Light-of-America. It flicker when connected to electronic dimmer. Goes off if tried to dim. ...................
I think dimming is over-rated! Although I do use dimmed lights as part of my theater setup (regular indoor floodlights). Those lights are used so seldom and for such a short period of time, any saving by switching to CFL's would be measured in fractions of cents (not even whole pennys).
And lets face it,
CFL's suck for reading light. A 20 watt high-intensity halogen is much better than a 14 watt CFL, and at a cost (electricity use) of 6 watts. I'd rather save my eyes.
Achieving the comtemporary home lighting scenes we all want, takes more than "dimming the lights".
In a room with widows on only one wall, a single bright table lamp (with a CFL bulb) on the windowless wall could be just whats needed to remove the shadows
on a bright sunny day. That night, in the same room, a couple up-lighting lamps (also CFL's) on the windowed wall and a raised (dimable) floorlamp near the center of room could make the room look warm and cozy.
Fortunately, creating these room scenes, at the push of a button (or a voice command), is where X10 really shines (pun intended).