Jason Snell, reporting for Macworld:
On Thursday, fall will come early for hundreds of thousands of Mac users when Apple releases its first public beta of OS X Yosemite. The public-beta program, announced during Apple’s annual developer conference in June, lets regular users download and test pre-release versions of OS X. Apple says the first million users to sign up at the OS X Beta Program website will be able to test Yosemite before the OS is released to the general public in the fall. Users who signed up will receive a redemption code to enter in the Mac App Store, at which point a Yosemite installer app will download to their Macs. Once Yosemite is installed, future updates to the beta software will come automatically via the system’s standard Software Update functionality. For much more detail about the public beta and how to install it, view our OS X Yosemite public beta FAQ. The first public build of Yosemite is the same one received by registered Mac developers earlier this week. Developers who are testing Yosemite are on a different track than regular users, however, and both groups may receive different updates at different times as testing continues. [...] When Yosemite is finished, users will be upgraded to the final version automatically, also via the Software Update feature within the App Store app. Before Mountain Lion was released in 2012, I tested it (on my main machine) via Apple's AppleSeed program. I continue in AppleSeed to this day, receiving early releases of Mavericks updates. That said, much as I'm tempted to test Yosemite, I'll probably hold out. My MacBook is decidedly not Retina, and I'm not so sure I want to use an OS so clearly (re-)designed for Retina displays.