iPhone firmware 2.0 is nearly 3 months away from release but the iPhone Dev Team has been able to jailbreak it. Firmware 2.0 for the iPhone isn’t fully baked yet so there is no way of knowing whether or not this jailbreak will still work when it is released in June.
It goes to show you that even with Apple allowing 3rd party developers the restrictions are still enough to cause some to want full access to the iPhone hardware. Maybe if Apple allowed developers to run applications in the background this wouldn’t need to happen.