The story was wrongly attributed to leftlanenews.com when in fact LLN was just referencing the National Motorists Association research at http://www.motorists.org/blog/red-light-cameras/6-cities-that-were-caught-shortening-yellow-light-times-for-profit/
The NMA is located in Waunakee Wisconsin, and for those who want to know more about the original research, they can read the article mentioned or contact the NMA at nma@motorists.org or (800) 882-2785.
The leftlanenews article that BoingBoing links to refers only to the motorists.org website but fails to mention the name of the National Motorists Association.

I was an animal caretaker in a research lab for a few years, and I took care of rats in cages. I have good reason to dismiss this as a hoax or at least, the result of human intervention.
1) It is unlikely that with the difficult of a "rat king" successfully finding enough food for all mouths, that all the subunits would live. If one member died, it would immediately, within seconds, be eaten by the others. Rats are cannibals and won't even wait for death to start eating a disabled fellow rat.
2) It is unlikely that that many rats would mysteriously be of such a similar age that they would survive together. Even if this sort of entanglement was possible, you would expect to see fragments of tails of the dead ones.
3) Rats usually go into burrows and tight places. This mass of rats would not be able to hide or locomote effectively. It would be taken out by a preditor.
4) There is no chance that this many rats could feed normally, unless they were in a bag of grain or a silo or nearly endless food store. Rats are competitive for food, so there would be deaths from fighting for resources.
5) Rat tails are not like string. They bend but are just flexible, still stiff enough that they would not get tangled like this. This was a prankster's macrame/weaving project, somebody with a bag of dead rats who went to some effort to carefully intertwine the tails. The result is as convincing as the Hodag photos of Rhinelander Wisconsin.

Garter snakes overwinter in protected places all balled up in a snake mass, but they successfully sort themselves out in the spring. For anyone who is still a believer, go watch a cage of rats for a day and I think their behavior will convince you otherwise.

State of the Union response:

http://www.antfarmjournal.com/AF-Journal/BushStateoftheUnion1-28-8/index.html

Great for high school reunions as well:
http://www.antfarmjournal.com/AF-Journal/BFHS77Reunion8-18-7/bigfootfunnies/Comic.html

Here is a funny art car I photographed in Spring Green Wisconsin in August 2007:

http://www.antfarmjournal.com/AF-Journal/ArtCarSpringGreen8-16-7/index.html

Here is an art car I saw in Spring Green Wisconsin on August 16, 2007:

http://antfarmjournal.com/AF-Journal/ArtCarSpringGreen8-16-7/index.html