Interesting. I found some links after a quick Google search:
http://www.flickr.com/groups/api/discuss/72157594497877875/
http://geobloggers.com/2007/01/24/offtopic-ish-flickr-ramps-up-triple-tag-support/
So we could do something like "event:running=carlsbad5000" or "event:cycling=granfondo". Defintely something to look into. Thanks, jakerome!
Looks very nice. I like the photos. You might want to change how the photos work so that it pulls photos based on a machine tag instead of relying on standard tags. This will ensure that the service will effectively be opt-in for photographers. I've gone and tagged a bunch of my photos, and now they show up on at least 5 events.