Using Python to add thumbnails to Explorer

[c d saunter]

Greetings All,
	In Widows Explorer there is a thumbnail view, where you see images as thumbnails.  
Applications such as MS Office and OpenOffice, when installed, cause their respective filetypes 
to be previewed as thumbnails as well. 

Thumbnails are stored in the Thumbs.db hidden file.

There my knowledge ends.  I'm asuming that aplications install registry keys somewhere that 
register an invocation that returns a thumbnail for a given file bit this is just a guess.

What I'd like to do is write some Python script that can be invoked to add thumbnails for 
certian file types (my own custom types and things like the .FITS array format.)

Googling isn't going anywhere so I am hoping there are some wizards out there with poiters...

Specifically any information on how the thumbnail system works would be great!

Cheers,
	Chris