It looks like Apple has already started sending out the beta version and SDK for the next iteration of the iPhone OS, 3.1, to developers.

The iPhone 3.0 software was released just about two weeks ago, ahead of the iPhone 3GS launch. By most accounts it’s pretty stable, though some users have been having battery issues. That’s why it’s a bit odd that Apple would iterate up to version 3.1 already, instead of something like 3.0.1, which it tends to do for minor updates and bug fixes. Could we be seeing a larger update to the OS already?

I’m told that there’s nothing much of interest in the release notes to indicate anything major that is new or changed.

Here’s the text of the email being sent from Apple:

iPhone SDK 3.1 beta and iPhone OS 3.1 beta are now posted to the iPhone Dev Center. These versions are for development and testing only and should be installed on devices dedicated to iPhone OS 3.1 beta software development. Please read the iPhone OS Pre-Install Advisory and the iPhone SDK 3.1 beta release notes before downloading and installing.

Update: I’m hearing a few reports that one change is that MMS is turned on by default. Perhaps AT&T is getting closer to turning it on as well in the U.S.