They work everywhere, but you have to give the doodle keyboard focus, otherwise you'll be typing into the search box. I think the only way to give it focus without clicking through to the [les paul] query is to hit record. Once you stop recording, though, you can still use the keys.
I wish it had octaves above and below though. It's hard to play anything in a minor key, because the relative minor starts on the 6th and then you only have like 4 notes above that.
I wish that the top row of keys would've given an octave higher, and the bottom row give an octave lower. That'd give you 3 octaves, enough to play a whole lot of songs.
http://www.google.com/webhp?tune=<encoded song here>
ex, do-re-mi from Sound of music http://www.google.com/webhp?tune=IAZxghAmCEEYYYZgQGAMMEMwARh...
ex: chopsticks http://www.google.com/webhp?hl=en&tune=wIBgRTAigBHIOEAhg...
seems to be a big hash w/note+duration encoded. Would hack on, but need sleep & moving to SF in a couple days. G'nite HN!
Edit: If anyone cares to figure out the recorded encoding scheme, could probably "record" or program a tune. ex: