Only if the bulb is designed for it, and don't expect it go to super-low either- most go to ~20-30% of perceived brightness and blink out. It's better if you figure out the light level you need, and buy the CFL that delivers it, or have switchable banks of lights for different levels.
Trying to design the electronics of a CFL ballast via cheap incandescent-dimmer waveforms or raw power-in is really tough task- too tough to fit in the li'l screw base where it has to live. Pin-base CFLs designed to fit into ballasted fixtures can dim quite nicely, with good efficiency over the dimming range. Most require special dimmers though.
Some of the better LED bulbs like the CREE LR6 (PAR/R30 bulb replacement) do a lot better, since there's more room to work with, and the luminous device itself runs at much lower voltage, with brightness determined by a single factor (junction current), whereas CFLs need to balance filament current, strike voltage and tube current for dimming. You'll pay quite a chunk o' change for dimmable LEDs that have any efficiency though. (Most don't come close to CFL efficiencies, hyperbole notwithstanding, but a few do.)