A quick paste from webmd:

It's a common belief that frequent typing can lead to carpal tunnel syndrome. But it's actually three times more common among assembly line workers than it is among data-entry personnel -- and frequent use of vibrating hand tools increases the risk. In contrast, one study found that even heavy computer use -- up to seven hours a day -- did not make people more likely to develop carpal tunnel syndrome.

end paste

I have also heard that bike riding can cause this too, the vibration in the handle bars being much like the tools mentioned above.

i know right. It is just weird.

Wow that is odd...