From what I understand:

Most incandescent timers run a small amount of current through the line all the time to power the timer portion of the device. This current will make a CFL flicker (as the ballast tries to get things lit without sufficient power) and will drastically reduce the life of the bulb.

All incandescent dimmers will act ‘weird’ with CFL bulbs, depending on how the dimmer works. There are ‘dimmable’ CFLs that may work with old dimmers. I haven’t had good results with them. They seem to take longer to turn on and “warm up”, and as a result, you need to get used to adjusting them to the light you desire.

If you’re buying a dimmer these days, look for ones that are CFL-safe. They’ll work just fine with normal bulbs, but will also work with CFL bulbs. Unfortunately, most (if not all) of the dimmers on the shelf at your local big box home improvement store are intended for use only with incandescent bulbs. Since the dimmers I unknowingly installed a few years ago were hideously expensive Lutron digital fade dimmers, I’m going to be stocking up on cheap A19 bulbs while I can.