If you didn’t upgrade your iPhone to OS v3.0 yet you might want to wait a little longer. The reason? Apple screwed a lot of things with that update. For example many iPhone owners can’t use WLAN anymore. Most of the camera assistance apps like ProCamera or NightShot break and can’t get repaired because Apple want it that way.

For details check the many discussion threads on one of the most failed updates in Apple’s history, eg.:

http://discussions.apple.com/thread.jspa?threadID=2044754