I can't believe I'm finally working on a functional photo album system for myself. I think I wanted this in about 2003, but everyone said you shouldn't build your own thing because it'll just be crappier than whatever existing open source application that already exists, and it'd be better to work on integrating the missing features into the mainstream tools.
But sod that. I don't think anyone else wants what I want, or if they do they're not so worried about silly little things (like storing photo times in UTC so they're properly ordered; as far as I can see, all photo album software just takes the Exif datetime and uses that). So I'm going to carry on building my own thing, and enjoying the satisfaction of making it just so.
Sorry Piwigo, and MediaWiki, and WordPress…