TG Daily has a writeup of some of the rumours and facts they heard about Apple's upcoming Mac OS X Snow Leopard operating system. The site claims the main focus of Snow Leopard is performance:
So we were told that Apple will "hit the pause on innovations" for Snow Leopard and focus on core enhancements instead. The company is re-writing large parts of the OS code in Cocoa that it recommends to developers as the preferred application environment. However, while Cocoa received a lot of attention, it is just a small part of much more significant code changes designed to leverage the so far largely untapped horsepower of multi-core processors and GPUs. In Snow Leopard, speed is the new green.
There is a certain kind of excitement behind this release as it may be one of the first applications that truly reveal how good modern hardware really is. That is in a stark contrast to Windows 7, which shapes up to be a maintenance release for Vista to clean up the interface, add a few features and correct some mistakes Microsoft has made with Vista. We know that Microsoft is working on an accelerated operating system that will take advantage of heterogeneous CPUs (with multiple CPU and graphics cores) and GPUs as well, but this new OS, according to our sources, will not be ready before 2011.
More info over here. Snow Leopard is expected to be released in June 2009 at Apple's WWDC.