Sue left a comment about the "This Bike Is A Pipe Bomb photo I used to illustrate my Yahoo Pipes article. I remembered the Ohio Incident with this sticker, but I had forgotten the sticker is for a a punk rock band.
Here's the Wikipedia article that probably has the most detail on the band, the labels, and -- count them -- three separate incidents of "bomb scares" because somebody thought a bomb would really be labeled as such. So, perhaps, the Boston bomb scare isn't as unusual as I might like to think.
Speaking of Pipes, I've found a couple of other useful cycling-related Pipes: This pipe keeps an eye on bike postings in the New York metro area. This Pipe is similar, looking for fixies for sale in Philadelphia.