I upgraded to the iPhone 3G this morning.
So it must just be the new 2.0 firmware
I think it is itunes with the issue. I have not updated to 2.0 but did update itunes 7.7 and ever sence a sync that would normally take a minute or less now takes 15-20 minutes. Yesturday it was taking 30-45 minutes and I did nothing else to itunes or the phone. I have to wait until later to update but I bet we will see another update to either itunes or the phone pretty quick.
You can just click the x when it's backing up. It will cancel the backup, but continue syncing like normal.
plus not only the back up but the normal sync of calendar and contacts is taking forever.