MacRumors believes that an error message posted to a database recording changes to the open source “launchd” framework, which oversees booting of Mac OS X and administers processes running on the system, might be the first public evidence of next generation Mac OS X. The text string in the error message contains 11A47 – a reference to the Mac OS X build number being used.

The website further explains, “Apple’s build numbering scheme utilizes a numerical prefix indicating the major release version, followed by a letter code indicating the minor release version and a numerical suffix indicating iterations of that version throughout its development. For example, the initial shipping version of Mac OS X Snow Leopard was termed Build 10A432 while the 10.6.1 update carried a designation of Build 10B504 and the 10.6.2 update released last week was termed Build 10C540. Meanwhile, Mac OS X 10.5 (leopard) carried a build number of 9A571 when it first launched.”

The build number 11A47 in the error message shows that 11 in the build number means the next generation of Mac OS X, and the 47 suffix indicates that the OS is in very early stage of development. MacRumors believes that Apple has been working on builds of the next major operating system revision for at least the last month or two.

However, our sources say that Apple started work on Mac OS X 10.7 almost a year ago, just after Mac OS X Snow Leopard was officially announced at WWDC in 2008. They also say that next version of Mac OS X will bring many new features and the UI will see a big upgrade. Our sources believe that Apple will first talk about the next generation Mac OS X at WWDC 2010, but the OS won’t come to the market before 2011.