People who have seen the emailed notice believe OS X 10.8.4 could see public release in the near future, possibly at Apple's Worldwide Developers Conference coming up on June 10.
Along with thanking participants who contributed to the testing, Apple noted the discussion board and Project Area dedicated to the seeding initiative will be shut down following scheduled infrastructure maintenance this weekend. No information was given regarding a public release date.
Though Apple has yet to dole out a Gold Master of 10.8.4, signaling an imminent release of the software update, the company most recently seeded the eighth beta version of the software last week.
While the maintenance update is not expected to have many new features, a beta issued in April revealed code pointing to support for the 802.11ac wireless protocol, hinting that future Macs could soon employ the speedy Wi-Fi tech. Last week, pictures of a reported Broadcom BCM94360CD PCI-E mini custom combo WLAN+Bluetooth card made the rounds, with some speculating that the part could be used in an as-yet-unannounced Mac.
Apple has announced that it will show off next-generation versions of OS X and iOS at WWDC 2013, but many are anticipating new hardware like a refreshed MacBook lineup featuring Intel's latest Haswell processors.