Not long after the release of beta 3, iPhone OS 4 beta 4 has landed on Apple's Developer website.  Though initial reviews of beta 3 were largely positive, past versions (beta 2) have been plauged with bugs and issues that we can only hope aren't present in beta 4.  If you have access to a Developer account, go get your download on and report back with your findings!

Update: Looks like beta 4 enables tethering for those heavy data users out there.  Upon installing, a popup can be found that directs users to call AT&T to set up internet tethering.  That being said, the nation's second largest wireless carrier has openly nixed the idea of tethering until "better network performance" can be attained, so don't get your hopes up.

Via Engadget Mobile