I read a interesting post on /. today. All it is talking about is, what you type on your keyboard (including the password), when recorded and analysis properly, can be discovered.
By the way, it is some kind of cryptanalysis, and with a quick search, I learn a little more (Acoustic cryptanalysis)!
Well, this remind me, there are some non-mechanical keybowrd, like using some kind of light-projected keyboard. Is it more secure in this sense?