A few days after it arrived in the Mac App Store, OS X Mountain Lion is off to a fast start. In 48 hours, customers have downloaded Apple’s latest operating system for Mac 2.11 million times, according to the Web tracking firm Chitika.

Priced at $19.99, Mountain Lion already accounts for more than 3 percent of all Mac Web traffic. Assuming that 90 percent of Mountain Lion users paid for the update, Apple likely generated $38 million in revenues in two days.

Like OS X Lion before it, Mountain Lion is available exclusively through a digital download.

The update includes a number of features brought over from iOS, including support for iMessage, a notification center, Twitter integration, and more.

Are you already using Mountain Lion, or are you waiting until later to purchase it?