According to The Times (reprinted here by The Australian), some recent Canadian research shows that learning to speak a second language helps to prolong the life of your brain and proetect against age related brain disorders such as Alzheimer's disease and dementia.

Bilingual older people have faster reaction times than those who speak only one language and are less easily distracted while completing mental agility tasks. The findings add to growing evidence that taking part in activities that stretch the mind has a lasting effect on brain health.

If I want a real challenge, I guess it's time to learn Danish ;)

I wonder if this extends to knowing more than one computer language? According to my CV I am fluent in about a dozen, but that doesn't count programming my HP48 ;)