"Devices updated to iOS 5 beta can not be restored to earlier versions of iOS," the Cupertino-based company reported wrote in an advisory to developers. "Devices will be able to upgrade to future beta releases and the final iOS 5 software."
The warning appears to indicate that developers opting to experiment and test their applications using iOS 5.0 on one of the company's iOS devices will be best advised make sure they install the software on a device solely dedicated to development purposes.
According to people familiar with the software, the note to developers accompanied the release of several pieces of pre-release software tied to iOS 5.0, including Xcode 4.2 Developer Preview (build 4C104 for Snow Leopard and 4D5031b for Lion), iTunes 5.0 beta (for activating iOS 5.0 on development devices), Apple TV Software beta (for mirroring content from an iPad 2 to an Apple TV over AirPlay), and iOS 5.0 itself (build 9A5220p).
Separately on Monday, Apple also equipped developers with Safari 5.1 Developer Preview and Mac OS X Lion Developer Preview 4 (build 11A480b), the latter of which contains about a half dozen known issues each for Mac OS X Lion and Mac OS X Lion Server.