I HAVE FOUND AN ANSWER!!!
i have an ipod nano (3g) and whenever my ipod is connected, nothing happened. NOW i have an answer!!!
in itunes press 'help' and then 'run diagnostics' an select the ipod connectivity tests (3rd down). After the test, in ports, press the button on the side and it should go to the apple help site for this particlar reason. this page is what you want -
http://support.apple.com/kb/TS1363?viewlocale=en_US
if you go through the steps then it should eventually work. mine worked after the second step (Remove iTunes). note: it doesnt just remove it, it reinstalls.
This saved my life!!! thank you for reading and i hope this gives success to most ipod users!!!