I tried a few experiments with it. Obviously my first instinct was to sketch Bruce Lee and see if it could find a picture of Bruce Lee. So I did:
And got this picture of a really fat sheep back:
It looks sorta like Bruce Lee I guess.
OK so it's not exactly useful as a search tool for pictures. But in addition to being fun, it can help find photos that match a certain colour scheme, if that was ever needed. I think it'd be cool to search for photos that were all, say, yellow and blue, then print them out and cover an entire wall of your house with the yellow and blue pictures. It'd be like paint...except with photographs.
I'd try this if it wouldn't cost a few hundred dollars worth of printer ink.