I was browsing through the internals one day (in the very merry month of January), and noticed that you can apparently change the data sent by the GPS from just location, to location + speed and location+speed+altitude. I lacked the cajones to actually make the change...don't want to brick my phone over something stupid.
Has anyone made any use out of this stuff yet? Perhaps someone could write a "Oops, I feel out of an airplane!" app.