Apple has released its third beta of iOS 8.3 to registered developers, following the public release earlier this week of iOS 8.2 to support the upcoming Apple Watch. This latest beta features a build number of 12F5047f and details few changes in the release notes from the prior beta, with minor issues related to CarPlay, WatchKit, and LTE Voice.

As expected, this beta also adds the Apple Watch app and related settings that were introduced earlier this week in iOS 8.2. This update is also accompanied by a new beta of the Apple TV Software, although it is unclear what has changed in that particular version as Apple TV betas are generally not accompanied by release notes.
Despite reports that Apple would release a public beta of iOS 8.3 around this time, there has been no indication from Apple of a public beta program starting as of yet — as with previous iOS betas, iOS 8.3 beta 3 remains available to registered developers only.
Update: The iOS Public Beta program is now available at Apple’s Beta Software Program site.