App idea, Any idea on implementation?

[Dr Mephesto]

Hi Guru's,

As a python newb, I was thinking about trying to implement a program
that converts whistled music into midi; the idea coming from a
proposed  application in the Mydreamapp competition hosted last year,
more details here: http://stratfordisland.com/whistler/

So, does anyone have a suggestion as to the best way to implement
this? I was thinking maybe a fast fourier ever 20th of a second,
selecting the dominant frequency, and then mapping that onto a real
musical scale, then stretching or cutting the notes to a preselected
timing scheme. Is this a stupid idea? Can one do a real time fourier
transform in python? Or is there some other way to find the frequency
of a whistle easily? I want to do this in real time, so as you whistle
a tune, you see the notes appear, but if this is too hard, the
prerecorded should be also good I guess.

Im just looking for some vague opinion on how to start, so please post
any idea you might have, every thing helps!  Also, If you know of any
code that already exist that might help, please post a link!

Thanks in Advance,
Dave