I recently came across this interesting little news piece. It's from quite a while ago (7 November 2001) so I don't know how I missed it, but I did. Anyway, it's worth quoting the first half (from ABCNews.com):

Not Just Another Pretty Face

The Brain Is Stimulated by Beauty, Study Finds

By Jeff Carpenter

B O S T O N, Nov. 7 — Money, drugs and beautiful women appear to have something in common when it comes to young men: The sight of a beautiful woman triggers virtually the same brain response in men as cocaine and cash do.

Researchers at Massachusetts General Hospital showed photos of "beautiful" women to 10 heterosexual men between the ages of 21 and 28. They found that "beauty" turns on the same reward centers of the brain that are activated in response to cocaine and money, the scientists report in the Nov. 8 issue of the journal Neuron.

The reward centers, which include the areas of the brain known as the nucleus accumbens, amygdala, hypothalamus, orbitofrontal cortex and ventral tegmentum, are considered to be evolutionary holdovers from reptiles and have been linked to a range of psychological disorders from addiction to depression....

(See also my 31 October 2003 and 23 June 2003 entries on physical attraction).