can you downgrade from 2.2 to a 2.1 or 2.0.2?

[tjobeid]

I have been unlocking phones for a while and came acrross some pain in the @$$ phones to unlock due to little errors and always got passed them after 2 days of trial and error. i was wondering if i upgraded and tried jailbreaking 2.2 and it acts up and crashed , can i just downgrade back to a 2.1?

And BTW im on a NON 3G iphone . o and can we unlock the 2.2 yet?