Boston's CBS affiliate reports:

Police are investigating four suspicious devices found at four separate locations throughout Boston.

Officials are telling WBZ the devices are similar to the one found this morning in Sullivan Square attached to a beam supporting I-93 north.

The four locations for these devices are the Boston University Bridge, Longfellow Bridge, Tufts New England Medical Center, and the intersection of Stuart and Columbus Streets.

WBZ has learned Boston police removed an item from the Boston University Bridge but they would not elaborate on exactly what the item is. Officers have since cleared that scene.

Charles Johnson adds, "Boston police now say all of the devices are ‘hoax devices’—and one of them contained a picture of a man ‘flipping the bird’ to police".

Apparently, up to to ten "hoax devices" have been discovered so far.

Update: Charles adds that "It’s turning into an ‘oh brother’ kind of day":

The latest news: the “devices” were part of a hare-brained advertising campaign by Turner Broadcasting, promoting the animated show “Aqua Teen Hunger Force.”

That must explain why I could have sworn I heard Ted Turner muttering something about the people of Boston being "thin, and they were riding bicycles instead of driving in cars"...

Another Update: More details here.

One More: Somewhere, Orson Welles is laughing his head off over this incident.