Apple's OS X Snow Leopard, which shipped in August 2009, continued to resist retirement last month, new data showed.
January statistics from Web analytics vendor Net Applications pegged Snow Leopard's share of all Macs at 28.2%, half a point higher than the 27.7% recorded by OS X Lion.
It was the fourth month in a row that Snow Leopard has been in second place, behind the newest edition, OS X Mountain Lion, but ahead of 2011's Lion.
The numbers illustrate the persistence of Snow Leopard, which has gained a reputation as Apple's version of Microsoft's Windows XP, an OS that stubbornly sticks around.
Meanwhile, Mountain Lion, which Apple shipped in July 2012, again gained ground last month at the expense of its predecessors, ending January in the No. 1 position with 34.5% of all Macs.
Approximately 7% of Mac owners ran 2009's OS X Leopard in January.
Mountain Lion will not remain at the top for long. Apple has committed to an annual operating system upgrade cycle, meaning that OS X 10.9 -- which has not yet been tagged with a feline moniker -- will likely launch this summer.
Unlike Microsoft, Apple has consistently convinced a significant portion of its customers to quickly upgrade to the newest operating system. Unless that pattern changes, by this time next year OS X 10.9 will be the most-used edition.
Snow Leopard users, however, have been more reluctant to upgrade than those running Lion, and the accumulating data hints at a longer-than-usual life for OS X 10.6.
Many have declared that they would not abandon Snow Leopard because it was the last that let users run applications compiled for the PowerPC processor. Although Rosetta, the translation utility that allows PowerPC software to run on Intel-based Macs, is not installed by default on OS X 10.6, it does automatically install the first time a PowerPC program executes. Neither Lion or Mountain Lion support Rosetta, and so are unable to run PowerPC applications.
But Snow Leopard users face a new security challenge this year: Oracle has just provided the final update for Java 6, and without Oracle's help, Apple will undoubtedly also halt its Java security work.
Java 6's successor, Java 7, runs only on Lion and Mountain Lion. That, along with the end of support, means Snow Leopard and Leopard are now out in the cold.
Net Applications measures operating system usage by tracking unique visitors to approximately 40,000 websites. More information about its January stats -- including problems Microsoft's Windows 8 has had growing its share -- can be found on the company's site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is email@example.com.