Apple announced OS X 10.6 named Snow Leopard as more of a performance release rather than a feature release.
Some of the announced changes include a smaller footprint (giving back some hard drive space), Microsoft Exchange support, extended 64-bit support to allow a theoretical 16TB of RAM, faster clock speeds with the multicore “Grand Central” technology, and QuickTime X which includes optimized support for the latest codecs.
It’s not known yet whether Snow Leopard is the beginning of dropped support for PowerPC by Apple. Several developers are reporting that their developer preview copy runs only on Intel machines.
The rumors are that this will be a free upgrade, but that hasn’t been announced yet.