Do you have a software firewall installed? I think I remember itunes using IP to talk to the background backup app.

Directly connecting my iphone to my mbp (instead of through a USB hub) helped cut down on the time for the backup.

That was also the case with the GM release, so this may be normal.

How much time does it take?

I can't remember exactly, but the whole upgrade process (including backup) needed somewhere between half an hour and an hour (on my 3G).

My update took about 45min (3G). But I don't have that much data on it, only ~4gigs.