iLife gets its long-rumored refresh in iLife '08, with iPhoto adding a new feature called "Events." It takes photo albums and organizes them as "events" automatically. "Instead of looking through 5,000 photos, you're just looking through 100 events." Defining events is customizable by time frame, and a day can be split into multiple events by simply picking the first photo of each and hitting split.
Mouse over an event in the library to preview, "called 'skimming'." You can pick a photo to represent an event. You can search by tags, sorted by event, and you can hide photos you don't want to see rather than deleting.