The fingerprint reader unlocks the gun in microseconds, but since it may not work when wet or in other adverse conditions, the PIN pad is there as a backup. [More]
That's all I need to know.
That and this stupid glove idea.
I'm thinking this should be an article but it'll take me a while with previous efforts already in development and with some serious contenders for my time that have been emerging from meatspace over the past couple of days.
[Via Steve T]