It has been revealed that Apple has already started testing a new version of Mac OS X Leopard. Labeled 9L14, the first reported Mac OS X 10.5.8 beta build is said to pack the usual bug fixes and tweaks, with roughly 27 fixes spanning areas like iDisk, iCal, Spotlight, and more.

Although Mac OS X 10.5.7 was believed to be the last incremental update to Leopard before the release of OS X 10.6 aka Snow Leopard, MacRumors now changes that prediction, claiming 10.5.8 will be available in our software updaters by the time Snow Leopard hits the shelves. “The new version of Mac OS X 10.5.8 offers the usual laundry list of fixes and changes to Leopard,” the report confirming the existence of 10.5.8 reads. “Apple specifically cites 27 fixes across iDisk, iCal, Spotlight and more. It seems likely that this release will be the final update to 10.5 before we see the introduction of 10.6,” the source alleges.

It shouldn’t come as a surprise that Apple has already begun to test Leopard for bugs, although it has released the 10.5.7 update only recently. Apple is extremely careful to patch any possible holes Leopard users may encounter, as well as to prevent the possibility of security problems arising. OS X 10.5.7 packed numerous fixes for security issues. These vulnerabilities, which emerge frequently and without warning, are also addressed with individual updates to Safari, iTunes, QuickTime, etc. As such, these main areas of Leopard are also likely to see updates around the time 10.5.8 makes its debut.

Mac OS X 10.5.8 will be an incremental update to Leopard, superseding Mac OS X 10.5.7 while adding its own changes. The Software Update will most likely arrive in tandem with a combo update, a security-only update (likely called Security Update 2009-003) and, of course, it will be available in Client and Server, PowerPC and Intel form.

More details about the first test build of Mac OS X 10.5.8 will be made available as soon as the seed notes for the respective build are leaked.