Various Web sites report that computers running on Apple's OS X 10.9 have appeared on their servers. If the news is to be believed, then Apple may be working on an update to OS X 10.8 Mountain Lion.

"Over the last month, we received page views from Mac OS 10.9 machines geo-IP located both on Apple's corporate network and in the Bay area. There are at least four different IP addresses that these hits are coming from, and the screen resolution on at least two of them is consistent with the 15-inch Retina MacBook Pro's display," reported 9to5mac.

9to5mac also reports that it is technically possible that the appearance of Mac OS 10.9 has been faked, but the "timing and IP addresses are in line with what we expect from beta testers of the next version of Mac OS 10.9."

AppleInsider reported that their Web site has seen more than 30 visits from machines listed running OS X 10.9.

Apple has been upgrading OS X on an annual basis for the last couple of years. The latest version the OS X 10.8 Mountain Lion, debuted on the Mac App Store in July this year, and OS X 10.7 Lion was launched in July last year. Assuming a similar launch pattern, Apple may begin releasing developers previews early next year with an official launch likely towards the middle of next year.

Recently, Apple sent invitation to developers to test OS X 10.8.3 and in September this year, Apple released Mountain Lion OS X 10.8.2, which added Facebook integration to Macs.

In 2011, Apple reported that more than seven million users have upgraded to OS X 10.8 Mountain Lion since the launch in July this year, which means that a high number of Mac users may upgrade to future updates.

We will have to wait and see if Apple will reveals OS X 10.9 soon and if it names the latest update in keeping with the current theme of big cats.