Evidence suggests Apple at work on Mac OS X 10.7
As first discovered by MacRumors, a new database entry for the open source "launchd" framework responsible for booting Mac OS X references "11A47" with a new error message. Based on Apple's numbering scheme, the numerical prefix of a Mac OS X build determines the version number, and 11A47 would suggest a reference to the next version of the operating system, Mac OS X 10.7.
When it shipped, Mac OS X 10.6 Snow Leopard carried the build number 10A432, and subsequent updates 10.6.1 and 10.6.2 had the prefixes 10B and 10C, respectively. For Mac OS X 10.5 Leopard, 10.5.0 builds leading up to launch were represented by the prefix 9A.
While the information suggests Apple has begun work on Mac OS X 10.7, as expected, it offers no hints or details as to what the next version of the operating system might offer.
Apple released Snow Leopard in August with great success, doubling the debut numbers of its predecessor, Leopard, and earning four times more sales than Tiger. Snow Leopard was given a warm reception due to its inexpensive $29 price and noteworthy performance boosts.