For anyone who has jailbroken or unlocked their iphone knows, when you update your iphone to a new OS, like OS 3.1 that just came out, you are going to lose your jailbreak and unlock. Re Jailbreaking 3.1 should not be much of an issue and I except an updated redsn0w to be out soon. Unlocking however, is another matter. Once you update to 3.1, it will change the baseband and thus re lock you to AT&T. No news on when that will be sorted.
So for now, if you are unlocked, just hold tight. I would also recommend holding off on 3.1 until a proper jailbreak version is out and tested. As for me, I’m having so many issues with AT&T around the ballpark area that I may give up jailbreak to see if 3.1 works any better.