Have you tried a hard reset? Hold the home button and the power button down at the same time until the logo appears. Turn the phone off and back on. Just something to try.
Wait. Am I missing something? How did you rebooted it, and resync if it will not unlock?
Called iPhone Tech Support this morning and described my situation. It appears to be a hardware issue. (I was able to get it to unlock once, and the keypad icons all responded very sluggishy!) I guess I'll be making a trip to my nearest Apple store (2 1/2 hrs away!) to get a 3G iPhone. All this happened just 36 days after the warranty expired on my original phone!
UPDATE! But not a good one necessarily. I spoke with iPhone Tech Support. I described my problem and what I had done to work around it...hard resets, restore, etc. They told me I had a hardware problem and invited me to send it in for repair. The repair cost would amount to the same cost of a new 8Gb phone!
My original phone was only 36 days out of it warranty!