Apple has released new versions of its iPhone OS and SDK for 3.0 developers via its iPhone Dev Center on the official Apple website. Available only to those enrolled in the iPhone Developer Standard or Enterprise Program, iPhone OS 3.1 and iPhone SDK 3.1 are now immediately available for download.

“With over 1,000 new APIs, iPhone SDK 3.0 provides developers with a range of new possibilities to enhance the functionality of their applications,” Apple tells developers on its website. “New APIs also provide support for applications to communicate with hardware accessories attached to iPhone or iPod touch.” The same stuff can be found in iPhone SDK 3.1 and then some.

Announcing the new Beta release, Apple says, “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. Use the Apple Bug Reporter if you discover compatibility or functionality issues while testing with the iPhone OS 3.1 beta release.”

Last month, Apple surprised developers by releasing Snow Leopard versions of the iPhone OS and SDK 3.0. Although the iPhone OS 3.0 SDK installer for Snow Leopard allowed for a simple installation of the SDK, they also had to make sure that Xcode 3.2 was already installed before installing iPhone OS 3.0 SDK. Whether or not the iPhone OS and SDK 3.1 Beta releases were also made on Snow Leopard remains to be confirmed.

Download iPhone SDK 3.1 Beta (Free)