Here's how this works - right now there's two categories: people and events. BUT if a person appears in a photo at an event, or in the group section, said photo will also be shown in their own personal category. The idea being that if you select, say, Phil Hackett, you will get every photo in the album that has Phil in it, even if he's barely visible! This means, of course, that some photo's will clearly be 'of' someone else, which isn't as cool as a photo that concentrates on the person you're looking for, so an attempt has been made to display the photo's roughly in order of relevance, so the 'only just appeared in this shot' photo's are bumped to the end. Hopefully.
11/07/2005 - As an addendum to the above, I've started favouring putting newer photo's to the front, when the person named is reasonably visible. Is all very arbitrary and messy!