Santa Rose isn't a processor it is a platform. It will allow for processors, eg merom to have a FSB of 800MHz as opposed to 667MHz, improved graphics, 802.11N wireless protocol and NAND which allows for super-fast boot-up using memory similar to ROM....? Not sure on that one.
I personally am waiting for it, as I'm to poor to buy a Mac now let alone an upgrade to Leopard next year, so I'll give it until May next year.
Cheers