I found this interesting quote from an article on harbourexchange.com today:
How can an iPhone measure the speed of the wind? There are no moving parts! Well the makers of this software have obviously spent too many hours on conference calls with heavy breathers like I have. The sound of someone sighing, panting, breathing into the microphone is irritating while discussing the annual business plan numbers, but it’s quite useful when you can take that principle and apply it to wind speed. Basically, the faster the ’sigh’ or ‘breathing’, the louder the sound, and it’s this that the makers of this application have harnessed for us sailors.harbourexchange.com, Top Sailing Applications for the iPhone, Oct 2009
You should read the whole article.