Apple released new versions of OS X Mountain Lion to developers today. Developer Preview 4 arrives with a build number of 12A239, while OS X Server Developer Preview 5 has build number 12S254j.
The release notes do not reveal any major updates to the software, but note a few minor issues with Setup Assistant, FileVault and QuickTime screen recording. Most significantly, the release does not ask developers to focus on any specific areas for testing, suggesting Mountain Lion will indeed be ready for release next month.
Mountain Lion was covered extensively at the WWDC Keynote this morning. It will be released in July on the Mac App Store for $19.99.