New submitter David Hames (3763525) writes Would you like to test drive the newest release of the Macintosh operating system? Apple is opening up the beta for Mac OS X Yosemite starting Thursday to the first million people who sign up. Beta users won't be able to access such promised Yosemite features such as the ability to make or receive your iPhone calls or text messages on your Mac, turn on your iPhone hotspot feature from your Mac, or "Handoff" the last thing you were doing on your iOS 8 device to your Mac and vice versa. A new iCloud Drive feature is also off-limits, while any Spotlight search suggestions are U.S.-based only. Don't expect all your Mac apps to run either. Ars has a preview of Yosemite.