The big news with After Effects CS3 is that it's not only written in Universal code (native for both PPC and Intel Macs), but it has a special feature called "Multiprocessing" which is enabled in Preferences. There is a check box that enables "render multiple frames simultaneously." When checked, AE spawns a process for each core called "aeselflink" and grabs up to 3GB of real memory per process. It's like creating a "render farm" within a single Mac.