I think it is brilliant that Apple is not advertising any new features in their next operating system installment for late 2009.  It’s something other companies could not get away with, but it’s acceptable for them to do so.  They will be focusing on performance, just increasing the speed and experience.
Of course there will be some new benefits

• Installation time will be drastically improved, they have reduced the footprint of many application significantly
• Grand Central – providing easier ways to leverage multiple processors and cores
• 64-bit Kernel – now you can take advantage of that 64 bit motherboard
• Exchange Integration – They will be using the systems and partnerships they have in place for the iPhone to bring Exchange integration to the Mac.  Outstanding.
• Safari 4 – Apple claims to have created the fastest implementation of JavaScript, and expects it to increase the performance of applications that heavily rely on JS by 50%.
• ImageBoot – you can boot off a network or secondary drive. Ideal for testing and development environments