Together with iTunes 8.2 beta a new iPhone OS 3.0 beta 4 has been made available to developers. There are no information about changes, but the
Spotlight.app is reported to be faster and issues with a crashing
Phone.app seem to have been solved.
As always: if you are no developer don’t install this beta, as you would need to download it from illegal places anyway. It is unstable and even if you were be able to jailbreak, you will not be able to unlock as this update also includes a baseband upgrade, that is currently not unlockable.
Don’t say we did not warn you!