You probably have incompatible software running under launchd and it is crashing constantly.
Check your Console application (found in Utilities) and see if there are logs showing up.
For me, Livescribe Desktop is broken under Lion, I see the following filling my logs:
Jul 22 07:11:50 Walkabout com.apple.launchd[1] (PenCommService[14433]): getpwnam("_pencomm") failed
Jul 22 07:12:00 Walkabout com.apple.launchd[1] (PenCommService[14434]): getpwnam("_pencomm") failed
Jul 22 07:12:10 Walkabout com.apple.launchd[1] (PenCommService[14435]): getpwnam("_pencomm") failed
Jul 22 07:12:20 Walkabout com.apple.launchd[1] (PenCommService[14436]): getpwnam("_pencomm") failed
Jul 22 07:12:30 Walkabout com.apple.launchd[1] (PenCommService[14437]): getpwnam("_pencomm") failed
Jul 22 07:12:30 Walkabout com.apple.launchd[1] (PenCommService[14437]): Exited with code: 1
Jul 22 07:12:30 Walkabout com.apple.launchd[1] (PenCommService): Throttling respawn: Will start in 10 seconds
Jul 22 07:12:40 Walkabout com.apple.launchd[1] (PenCommService[14440]): getpwnam("_pencomm") failed
Over and over. This can spike CPU usage for the launchd. Probably something similar for opendirectoryd as well (there are known issues with network mounts in Lion (they changed netatalk to version 2.2, and most NAS servers are not compatible). You should be able to get more information in the logs, post them here for additional assistance.