These things also are not supposed to be used covered by a bulb or upside down. (link I found the quickest http://www.apartmenttherapy.com/when-you-shoudnt-use-cfl-bul... )

I've seen local ordinances that in effect mandate the incorrect usage of CFLs. As such, a fixture at my mom's house results in a burned out (due to overheating) CFL about once every 6 months.