Apple previewed the next OS X version 10.6 Snow Leopard to developers today at the World Wide Developers Conference 2008 (WWDC08) and briefly posted details (the page was later pulled) on their web site.
Details included:
Snow Leopard is optimized for multi-core processors, taps into the vast computing power of graphic processing units (GPUs), enables breakthrough amounts of RAM and features a new, modern media platform with QuickTime® X. Snow Leopard includes out-of-the-box support for Microsoft Exchange 2007 and is scheduled to ship in about a year.
The posted information also mentioned that Safari will have a much faster implementation of JavaScript, increasing performance by as much as 53%, making Web 2.0 application feel more responsive.