I have the same problem as JGiers, I think.
Just plugging my phone in doesn't make it sync, but I can access the files in my Compyet -> Portable Devices.
Only when I start the Mobile Device Center is starts to sync. After I did the I can close the Mobile Device Center, connect my phone again, and it will sync automatically like it should, until I reboot and the trouble starts all over again.
I noticed after I connect in the Mobile Device Center it will keep a Sync Center icon running in my systray, I guess the problem is Sync Center isn't started automatically when I boot my PC. But how do I start Sync Center on boot without bugging me with any windows, I just need it to run in the systray.