[blobbers]

Apparently the attacker has never seen my macbook air running a heavy compilation job. Fan is cranked and the keyboard is so hot that there is no way they are getting my password!

Nothing but noise to a thermal camera...

[nomel]

Maybe they would look for cool spots. I assume you would only run into problems where the key was the same temperature as your finger.

[blobbers]

I was half making a joke... but I believe if you have a large external thermal source or sink the time for keys to renormalize would be dramatically shorter.