Today is International Pillow Fight Day: photos, video and serious pillow fight problems

Here's the main website.

Update: Mental Floss has 10 Pillow Fights That Caused Serious Trouble

There are events already organized in a lot of cities, including (local to me) on the Mall in Washington, D.C. (although I'd rather attend the event in Rome; aside from the fact that I would be in Rome, their version last year involved superhero costumes).

If you would like to learn how to organize a pillow fight, read the howto guide. Here's an article from the Washington Times, one from Syracuse.com (which has a LOT of photos) and some video footage of the 2013 NYC event: More at Buzzfeed.

and in London: