Apple's recently released Mac OS X 10.5.6 is causing a few minor issues for iPhone users. Some users have reported an inability to synchronize with iTunes after the update. An Apple Discussions poster writes:
"I have just upgraded my MacBook Pro (Intel G5) from OS 10.4.11 to 10.5.6. It was a seamless upgrade. However, I noticed when I plugged in my 15-day-old iPhone (not jailbroken, version 2.2) to sync, it failed to appear in iTunes. In fact, iTunes didn't even open. Bizarre! Everything was working fine before the upgrade. I'd love to hear some thoughts. I don't think this is a USB issue."
This issue can generally be resolved by simply downloading and reinstalling the latest release of iTunes.
Users are also experiencing an inability to recognize iPhones in DFU mode. A potential fix involves replacing some of Mac OS X 10.5.6 components with files from 10.5.5 -- particularly kernel extension IOUSBFamily.kext. A safer fix is to archive and instal then reinstall Mac OS X 10.5.5.