Downgrading 3.0 back to 2.2.1
If you are on the beta and find it to be way to buggy for daily use, which is to be expected, simply downgrade with instructions below. [Via Bigboss]
The following is for a Windows PC - for a Mac check out the link above. I used my Windows machine over my Mac for simplicity.
1 - Open iTunes
2 - Get your iPhone in DFU mode
3 - Select restore iphone (using the original 2.2.1 firmware, not a custom one)
4 - Let your iPhone do the restart process until you get ERROR 1013
5 - Close iTunes
6 - Open Quickpwn. you will get a message saying to hold power and home for 15 seconds.
7 - Turn on your iPhone by holding power button for 2 seconds
8 - Open iTunes and your iPhone is recognized and activated