Ableton announced that Live 5.2 will support native Intel-Macs. According to their web site "Live 5.2 will enter beta as soon as the new Intel Core Duo-equipped MacBook Pro is available, and expected to be released in February. Thanks to Live 5.2, early MacBook Pro buyers will be able to run Live immediately and enjoy substantially higher audio performance than on today's fastest Mac notebook."
In this same press press release, they mention their goals for Live V6 as "support for multicore/multiprocessor architectures, to the benefit of both Windows and Mac OS users. This feature will bring users of Intel Core Duo-equipped Macs another large increase in audio performance, and Windows users will be able to fully exploit the speedup potential of the various available multicore/multiprocessor hardware solutions the market offers."