Registered developers have had access to the Mac OS X 10.8.5 update for quite some time now. The update brings a number of crucial bug fixes for Mail, Wi-Fi and other features. Apple has finally released OS X 10.8.5 update to the public.
Apple might release a new OS X Mountain Lion update today which has been in developer preview stage for a couple of months. The company has reportedly already shipped pre-release builds to partners, and it may release OS X 10.8.5 later today.