iTunes does not recognize that I've plugged my iPhone in

I probably last synced my iPhone yesterday morning. But when I plug it in now, iTunes does not seem to think there is anything plugged in at all. I've rebooted my Mac (MacBook Pro 10.6.8), I've rebooted my phone (iPhone 4 4.3.5) and I've swapped the cable out. All to know avail. Also, since I have a wireless mouse, I moved the USB receiver over to the port I normally plug the sync cable into, and it works fine. I do find the following in the console logs:

9/6/11 9:15:15 PM com.apple.launchd[1] (com.apple.usbmuxd[984]) posix_spawn("/System/Library/PrivateFrameworks/MobileDevice.framework/Versions/ A/Resources/usbmuxd", ...): No such file or directory

9/6/11 9:15:15 PM com.apple.launchd[1] (com.apple.usbmuxd[984]) Exited with exit code: 1

9/6/11 9:15:15 PM com.apple.launchd[1] (com.apple.usbmuxd) Throttling respawn: Will start in 10 seconds

I looked, and indeed the file is not there. I would think that the file is root owned and I can't imagine anything I could have done that would have deleted it, if indeed that's the problem.

Any ideas?

-- Rob