Native Instruments does not recommend, or offer technical support for, using its products within the "Rosetta" environment on Intel-based Macintosh computers. (Please note that, according to Apple, Logic 7.1 does not run within the Rosetta environment either.)
New Native Instruments product releases and updates will continue to support PowerPC-based G4 and G5 Macintosh computers until further notice.
Users of third-party instruments based on KONTAKT, KOMPAKT or INTAKT technology should contact the respective manufacturers for information about support for Intel-based Macs.
No updates will be released for older or no longer available versions of NI products, such as ABSYNTH 1/2, REAKTOR 3/4, GUITAR RIG 1, REAKTOR SESSSION, B4 (Version 1), PRO-5/52, TRAKTOR DJ Studio 1/2.x.
Rosetta sucks, it's dirt slow. At work I use a 1.6 GHz Core Duo Mac mini and opening apps like Photoshop is teh suck. My older 1 GHz TiBook runs Photoshop much faster.
Logic and Reason both have UB compatibility now and Steinberg is doing a public beta of a Cubase UB release, so things are getting there, but unless your money is burning a hole in yer pocket it might be good to wait until more stuff is UB and probably until Apple works out the kinks in first generation hardware. (UB = Universal Binary)
I read recently that they apply obscene amounts of thermal paste in the MacBooks like they do in the MacBook Pros and that they run crazy hot.