It looks as if Apple might be preparing to publicly launch OS X 10.8.5, as the company has reportedly seeded a new prerelease version of the OS to its employees. The seed is marked as build 12F35, two builds higher than the most recent developer seed, released more than two weeks ago.
While a prerelease build for Apple employees is frequently indicative of an imminent public launch, it is not always the case. As was seen with OS X 10.8.3 back in early March, Apple issued a prerelease build to employees but then elected to distribute a new developer build roughly a week later with a public release following two days later.
MacRumor’s source says the build includes final release notes for the update, highlighting fixes for Mail, AFP file transfer performance, screen savers, and Xsan.