Apple announced Monday that downloads of the latest OS X, Mountain Lion, had exceeded three million in just four days, making it the most successful OS X release in the company's history.

With over 200 new features, Mountain Lion, the ninth major release of the advanced desktop operating system, is sold on Mac App Store as an upgrade to Lion users for $19.99.

Unlike Mac OS X v10.7 Lion, Mountain Lion is not available to be upgraded on a USB flash drive. Last year, Apple revealed that Lion downloads totaled more than one million in one day from the App Store.

It implies that Lion continues to hold the biggest number of downloads after 24 hours of its release. However, there is little or no proof to ascertain the company's assertion. Reports published in the Apple Insider indicate that within 48 hours of its release, OS X 10.8 Mountain Lion hit 3.2 percent penetration rate.

The Apple Insider article was based on reports submitted by Chitika Insights, the research arm of ad firm Chitika that monitors and analyzes web traffic across its network.

A report from The Droid Guy stated that only paid customers were able to download Mountain Lion. New owners of Mac can only upgrade their machines under the terms of Apple's 'Up-to-Date Program,' which would not be provided until 72 hours after they submitted request. The program offers free upgrade to Mountain Lion to users who bought a Mac computer after June 11.

Mountain Lion's price at $19.99 is less than that of its predecessor and sells at half the price of what Microsoft will charge to upgrade to Windows 8 Pro starting October 26.

Apple Seeds Mountain Lion OS X v10.7.5, iCloud Control Panel With Developers

The Cupertino tech giant made another important move July 30, seeding new builds of OS X Lion, Lion Server and the Windows-only iCloud Control Panel beta with developers.

The Apple Insider noted that with the new builds identified as 11G30 for OS X Lion and Lion Server, Apple is urging developers to focus on graphics performance and quality as there were no known issues with the release.

Work on the server side was reported to be substantial as developers were tasked with focusing on password server, profile manager, webmail (round cube), server app, system image utility, software update server, web sharing and workgroup manager. No issues were reported in the server build either.

The Apple Insider indicated that the second seed for version 2.0 of iCloud Control Panel brings a host of new features to the Windows-centric software including consolidation of mail, contacts, calendars and task enablement in a single checkbox and overall stability enhancements.