According to Web measurement firm Net Applications, Lion accounted for about 44% of all copies of OS X that powered Macs which were online last month. Since the beginning of 2012, Lion's share has climbed 12 percentage points.
Because of the impending release of Mountain Lion, it's quite possible that Lion will peak this month. If Lion gains share at the average tempo of the last six months, it will climb to just over 46% of all Macs by the end of June, then begin a gradual slide as users migrate to Mountain Lion.
Lion's share line will probably begin to resemble the one seen here for Snow Leopard, the OS X that has slipped since 10.7's debut in July 2011. (Data: Net Applications.)
Along with Snow Leopard, which last month had a 40% share of all OS X systems, the vast bulk of Macs in use -- 84% -- may be eligible for the upgrade to Mountain Lion.
Apple accelerated the abandonment of OS X 10.5, or Leopard, in April when it began handing out free upgrades to Snow Leopard to users of who were still on the older OS. In April and May, Leopard use dropped from 13.6% of all Macs to 12.3%.
Although those free upgrades were intended primarily to prepare Macs for the June 30 disappearance of MobileMe -- that deadline is when the newer iCloud online sync and backup service becomes Apple's sole cloud offering -- it also made some of the machines able to qualify for the Mountain Lion upgrade.
Many of the features that Federighi demonstrated today were ones that have been leaked since the February 2012 release of the first Mountain Lion developer preview, but scores of others had not been widely discussed, including system-wide sharing of photos, videos and other files; future integration with Facebook; an OS X version of Game Center, Apple's under-utilized multi-player gaming portal; and voice-to-text dictation from within any application that accepts text input.
Mountain Lion will also come with a new edition of Apple's Safari browser, version 5.2, that will a single address bar-search field similar to Google Chrome's, an offline reading list tool, and "iCloud Tabs," which synchronizes open tabs in the browser across multiple devices, including the iPad, iPhone and other Macs.
Safari 5.2 will also support the "Do Not Track" privacy option that lets users signal to websites and online advertisers that they don't want their movements on the Web monitored.
Also on Monday, Apple confirmed that it will again provide free upgrades to Mountain Lion to customers who buy a new Mac with Lion pre-installed. That program, called "Up-To-Date" by Apple, goes into effect today and continues as long as either Apple or its authorized resellers sell Lion-powered machines.
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