It's almost exactly one year since OS X 10.7 was released, but OS X (no longer "Mac OS X") 10.8 has been released and is available for purchase and download in the Mac App Store for $19.99 USD. Unlike 10.7, 10.8 is not available for purchase on any physical medium.
I haven't updated yet, although I'd like to. Just as an alert, anyone using Mail or Safari for RSS should be aware that in 10.8 the RSS functionality has been removed from those two applications. You will now need to find a different application to handle your RSS feeds.