During a week following Mountain Lion's release, its share of the Macs that accessed Chitika's network was a puny 0.06%, or six out of every 10,000 Macs.

But that was nearly three times the percentage of Windows users running Windows 8 who were served an ad in the early days of that operating system's availability. In the same period following the release last September of Windows 8 Developer Preview, just 0.021% of all Windows PCs were powered by that sneak peek. (The number represented 2.1 PCs out of every 10,000 running one Windows flavor or another.)

Chitika regularly mines its ad impression data for trends in operating system and browser usage patterns.

of Mountain Lion, otherwise known as OS X 10.8, on Feb. 16. Microsoft launched its Windows 8 Developer Preview on Sept. 13, 2011.

Since that second date, Microsoft has also , a more polished version of the build it distributed last year.