Agree, I have not seen dimmable ones before.
Overall I have had a negative experience with CFLs, spent perhaps $200 a few years back and retrofitted nearly all the bulbs in our house where the fixture could mechanically fit a CFL. Results very poor - dim compared to the incandescent bulbs, yellowish light, flicker, many/most of the bulbs burned out after 1-2 years or so despite 7 year warranties, and 2 of them "smoked" during the failure process. Found also that they work very poorly as outdoor/garage bulbs when its cold - they are VERY dim in cold environments.
For a while I tried to work with the manufacturer (Feit Electric) to get replacements but after 2 of them smoked I just gave up on the concept. We're back to incandescents.
I think its a great idea to replace incandescent lighting with something more efficient, but what I saw of CFLs made me think this concept isn't ready for widespread deployment. I'm not touching CFL technology again any time soon, I think LED based lighting is the way to go.