The unlock for first generation iPhones will remain the same. Bootneuter. If your phone is unlocked it will keep its unlock even after a restore to 3.0 b/c the baseband doesn't change. Makes things easy.
what about activating the phone? if i'm on 2.1 and upgrade to 3.0, i understand the sim stays unlocked, but does the screen lock to the emergency call window only, or will it bring up the home screen? if upgrading to 3.0 requires i reactivate than i'll have a brick again since i don't have an iphone account.