A new beta version of the iPhone OS 3.0 and associated SDK has been released by Apple. You can upgrade your iPhone is you have been using the beta 3 to experience greater stability, some enhancement in MMS support, Apple Push API and probably some more.

Note that:

• you'll need to upgrade to the pre-release version of iTunes 8.2 to be able to use this version of iPhone OS
• you won't be able to deploy applications on iTunes using this SDK
• your iPhone would not be able to revert to iPhone OS v2.2