[scottcha]

I believe temperature sensors are required to get barometric data to altitude[1]. That's why all altimeter watches also have temperature though its usually useless while wearing since its reading the temp of your wrist instead of the air.

On a second note I produce an app (http://www.ullrlabs.com) for avalanche danger evaluation and knowing your ambient air temperature is one factor which is helpful in that process. Though I haven't yet tried to read that value on android phones for the app.

[1]See pressure altimeter calibration equation: http://en.wikipedia.org/wiki/Altimeter

[Recoil42]

Your first note is irrelevant, since all modern phones have a (hot) CPU running while the phone is active. It's why phones don't rely on their temperature sensors for ambient readings in the first place even if they have them.