That was fast. Folks on the modmyifone.com forums are claiming that the iPhone Dev Team - that elite band of iPhone hackers - has already unlocked the version 2.0 firmware distributed as part of the SDK (Software Development Kit) last week. The firmware won't be released to the public until June, and contains a number of new features including Contacts Search, Parental Controls, and support for Exchange Server corporate email and Apple's "App Store" for purchasing and installing third-party software.
Dev Team isn't releasing the hacked firmware for fear of legal action from Apple (technically it would constitute leaking an unreleased product), and also giving Apple the means to counteract the unlock before the June release date. Currently there's a screen shot of the unlocked firmware posted to the forums, and a YouTube video showing off the hack - and iPhone 2.0's new features - is promised in the next few days.