"The school is quite happy for them to take photos after the production but not during it, " Ms Kendall added.

BBC: News | Education | School bans videos of Christmas play

It is why these hats, and their wearers, cause spectators at the Derby to take pause, snap photos and vote for them in contests.

CNN: Crowning glory: The art of Kentucky Derby hats

So for example, Foursquare might some day be able to let users take photos in-app and upload them into Facebook photo albums.

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