Hi,
Can you access the camera in any other App ?
Photo Booth and iMovie would be my first choices.
If you have another Mac Users Account on your computer does the camera work in that account (try the same apps) ?
Create an Account in System Preferences > Accounts if you don't have anything but your account and the Guest one.
IF you go to the Apple icon top left and Hold the ALT key you will see the second item change to System Profiler.
Select this then open the triangles to see Hardware > USB
Does the iSight appear here ? (You may have to click the USB Bus items on the right to get the details to show in the lower pane).
If you have tried the SMC/PMU resret and your accounst still can't see the camera then try a Safe Boot
Once it has started up this way restart the computer normally.
8:14 PM Saturday; July 30, 2011
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb( 10.6.8)
Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images." No, Seriously