Apple's new 64-bit Macs should be out soon. Higher hardware clock speeds will be available. The new 64 bit Mac OS X will come later (after the hardware has been made available).
See eWeek's story here,
and The Register's story here.
I found out about this news from Francois' FS Consulting weblog.
Note for JT (by JT): contact Francois about possible collaboration (his site: winesearch-online.com, my domain: wineries.us