Via Slashdot, I read Soviet Scientist Turns Foxes Into Puppies, where I found these links to documentary excerpts. I don't know what brought these breeding experiments into the news--most of the related stories I found are at least a few years old. However, it was news to me, and offers some fascinating suggestions about how domestic animals came to be that way. Here's the abstract of a review article, Early Canid Domestication: The Farm-Fox Experiment, by Lyudmila Trut (1999):
Abstract: At an experimental farm in Novosibirsk, Siberia, geneticists have been working for four decades to turn foxes into dogs. They are not trying to create the next pet craze. Instead, author Trut and her predecessors hope to explain why domesticated animals such as pigs, cattle and dogs are so different from their wild ancestors. Selective breeding alone cannot explain all the differences. Trut's mentor, the eminent Russian geneticist Dmitri Belyaev, thought that the answers lay in the process of domestication itself, which might have dramatically changed wolves' appearance and behavior even in the absence of selective breeding. To test his hypothesis, Belyaev and his successors at the Institute have been breeding another canine species, silver foxes, for a single trait: friendliness toward people. Although no one would mistake them for dogs, the Siberian foxes appear to be on the same overall evolutionary path--a route that other domesticated animals also may have followed while coming in from the wild.
You can download the complete article: Early Canid Domestication: The Farm-Fox Experiment (pdf file). It's well worth reading, and not painfully technical. (That's my evaluation, but I've been told I'm a painfully technical kind of gal, so YMMV.)
A 2006 New York Times article describes some related research on rats: Nice Rats, Nasty Rats: Maybe It's All in the Genes.