During today's Apple earnings call, CFO Peter Oppenheimer announced that Mac OS X 10.7, better known as OS X Lion, will be launching tomorrow on the Mac App Store. Lion will be available as a 4 GB download, and will sell for $29.99. Once purchased, you can install it on all Macs that you own at no extra cost, and without any sort of authorization key. Apple is touting 250 new features in Lion, with things like Launchpad (an app launcher that is reminiscent of iOS,) Mission Control (a replacement for Expose,) Resume, touch gestures, and more included. Lion Server will also be available as a $50 add-on.