Update: Yosemite has shown up on the Mac App Store for download, though some users are having trouble connecting as usual.
The world first got a glimpse of Yosemite at WWDC in June. The annual desktop OS update includes a more modern look, new cross-functionality with iOS devices and expanded search capabilities. Apple is also touting new iCloud Drive cloud storage features and a major update to its iWork productivity suite.
Apple ran a public beta for OS X 10.10 this summer, granting more than 1 million users early access to the update.