"Not for use with Control Devices" are the words we see on many CFL sites, meaning that you are not supposed to use then with dimmers (this is more obvious) but also not with timers, light sensors (dusk-on switches) and motion detectors.
When I first bought CFLs from a website called 1000bulbs.com, they were selling the SatCo brand, and I installed them in all fixtures, one with a motion detector and two with light sensors with no problem (actually I hadn't noticed the warning.) Later bulbs, however, of a different brand, burned out in a few days when so installed. I wondered why. It was difficult, even in these days of the ubiquitous wiki and other sites, to get that information.
Turns out that most control devices use a constant, very low level of current, to maintain their state (in the case of timers, to run the clock,) which is routed through the bulb or bulbs they control...which is why, when your bulb burns out, your timer stops as well. This tiny current has no effect on incandescent bulbs, but for some reason damages the electronics in CFL's. Voila...CFL burn-out.
Of course, you may wonder why the CFL manufacturers cannot account for this tiny flow, but that may be another story.
This works for many multi-socket hall lights, or multiple outside lights on the same timer, for example. The incandescent bleeds the vampire current and keeps the CFL's safe. Unfortunately there's a lower limit to the wattage of the bulb and 15w seems to be the minimum; if you use less, the CFL's get too high a proportion of the current and damage ensues.
Of course, you increase your energy usage a bit, but if you have, say 2 CFL's and one incandescent, you're saving 60% instead of 75%.
Or you can pop for special control devices that control CFL's...hard to find, and not always easily installed as they require a "neutral wire" in the switch box, which is not always there. You can use the ground, but that's against code, so I didn't say it.
One such device that actually knows when dusk and dawn are reached and switches lights on or off at varying times during the year (you have to program it with the latitude and longitude of where you are,) is the Aube Solar switch in the image.
It can handle all kinds of loads, including CFL's and small motors. Note that, unlike a regular wall switch,it has three wires, not two. The third is the above mentioned neutral wire. So it can only be used where the switch box has an incoming neutral wire.
But it won't burn out your precious CFL's.