By Kasper Jade

Published: 07:15 PM EST

Apple is quietly preparing to equip some of its developers with the first pre-release copies of Mac OS X 10.6 Snow Leopard since an inaugural build was issued to attendees during its annual developers conference in June, AppleInsider has learned.

People familiar with the company's plans suggest that distribution will be extremely limited, as the software is believed to have undergone a number of enhancements since its earlier appearance. Members of the vast Apple Developer Connection network are among those who are unlikely to see the new builds, they say, at least during the initial phase.

Unlike major Mac OS X releases of years past, Mac OS X 10.6 Snow Leopard will mark a temporary departure from user-oriented feature implementations in favor of a focus on performance and stability. This will include a tremendous amount of effort towards laying a foundation that will support the future directions of the microprocessor and graphics industries for years to come.

With the chipmakers indicating that the future of PC performance will largely be driven by an increase in the number of cores per processor, rather than raw clock speed, Snow Leopard will include a feature called Grand Central, which will allow developers to easily author applications that take advantage of 2-, 4-, 8- and even higher-core Macs without extensive knowledge of multi-threading and load balancing.

Similarly, a feature called Open Computing Language (or OpenCL), will let any application tap into the vast gigaflops of GPU computing power previously available only to graphics applications. Snow Leopard will also raise the software limit on system memory up to a theoretical 16TB of RAM and introduce a new version of QuickTime optimized for modern audio and video formats.

Word that Apple is set to expand testing of Snow Leopard comes just weeks before the company is expected to return focus to its Mac business with the introduction of radically redesigned MacBooks and MacBook Pros. Mac OS X 10.5.6, the next update to its existing Mac OS X 10.5 Leopard operating system, is also expected to surface around that time, and has been rumored to include native Blu-ray support.

Since its pre-release debut in June, AppleInsider has covered a number of smaller discoveries surrounding Snow Leopard, such icon support of QuickLook, dramatically smaller application packages, and the system's new multi-touch framework and text processing features.

We've also recently kicked off our Road to Snow Leopard series with a four-part segment covering upcoming improvements to 64-bit support, and offering readers a look at how those under-the-hood enhancements will benefit every day use:

Road to Mac OS X 10.6 Snow Leopard: 64-bits

Road to Mac OS X 10.6 Snow Leopard: 64-Bits

Road to Mac OS X 10.6 Snow Leopard: 64-bits, Santa Rosa, and more

Road to Mac OS X 10.6 Snow Leopard: twice the RAM, half the price, 64-bits

Road to Mac OS X 10.6 Snow Leopard: the future of 64-bit apps

Additional Snow Leopard news is aggregated on our Snow Leopard topics page.