Anytime there's an update -- or in this case, even a new beta firmware for developers to test out months ahead of an update -- the iPhone Dev Team reminds Jailbreak users, especially those running unlocked using YellowSn0w to stop, breathe, and wait for the "all clear" before updating.
In this case, the Dev Team says:
If you find yourself with access to the 3G IPSW for 3.0 via the iPhone Dev Center program, and you are using yellowsn0w, do not update or restore to that official IPSW. You will lose yellowsn0w and find yourself unable to revert the baseband to get it back.
And for those wondering, yes the 3.0 OS is jailbreakable on all devices. It’s just those using 3G yellowsn0w that have to show some restraint and wait for PwnageTool to create a custom IPSW that avoids the baseband update.
No big surprise they can crack the 3.0 firmware, though Apple might still throw some curves their way in future betas or the final release. We're guessing the true next step in the cat and mouse game will be iPhone 2,1 hardware, which could prove as tricky, if not trickier, than the iPod touch 2,1 which took quite a while to get to RedSn0w...
(Thanks to everyone that sent this in!)