Hackers calling themselves the iPhone Dev Team got ahold of the new firmware that ships with the SDK (version 1.2 as beta, but is to be released as 2.0 to the public) and reported they had "already decrypted the disk image and jailbroken the firmware." The "Jailbreak" apparently only works with hacked activiation, meaning it currently doesn't work with AT&T iPhone's. [more]
To read more, visit http://www.modmyifone.com/forums/showthread.php?t=62591 or http://www.informationweek.com/news/showArticle.jhtml?articleID=206903250