One of the big stories from Apple's WWDC 2012 keynote last week was OS X 10.8 Mountain Lion. The latest version of Apple's desktop operating system packs in a bunch of exciting new features, including Notification Center, Reminders, Twitter Integration (and probably Facebook, too), and more. They also announced the price - a positively shocking $19.99.
One thing they did not announce, much to the disappointment of many, was Mountain Lion's release date. All they said was that it would be shipping "next month." Of course, "next month" (i.e., July) is still a fairly broad window, and Apple has declined to narrow it down.
One recent report, though, puts a firm date on Mountain Lion's release. According to Three Guys and a Podcast, who apparently have a source in San Francisco's Bay Area, Apple is planning to launch Mountain Lion on July 19th. This keeps Apple's releases on a yearly schedule, a format of which Apple has grown increasingly fond, particularly with iOS products.
Like Lion before it, Mountain Lion will only be available as a download from the Mac App Store. Once it's released, you can upgrade to Mountain Lion from any Mac that has the correct hardware specs and is running either Snow Leopard or Lion.