If you don't have Snow Leopard, iLife '11 is a no-no
iLife '09 was certainly moving toward an Intel processor requirement, but iLife '11 has made the transition complete with even tighter requirements. You have to have an Intel-based Mac, of course, and that Mac has to be running Snow Leopard.
It's not a giant surprise; things have been slowly rolling that way, both from Apple and other Mac software developers. If you are still running that big Mac G5 desktop or one of the older non-Intel laptops the walls are slowly closing in on you.
Also note that iLife '11 really wants you to have only the latest version of the software suite. An install will upgrade (replace) iLife '09, so once you pull the trigger there is no going back. Consider yourself informed, and warned. Do you feel it is a mistake for Apple to leave so many customers behind, or are you OK with the new requirements?
iLife '09 was certainly moving toward an Intel processor requirement, but iLife '11 has made the transition complete with even tighter...