Detect object speed? I have some objects that I need to know how fast they are going. I have a property, "speed," and I would like it to show the object's speed in blender units. For the unit, it doesn't matter that much as long as I can read it. Python or logic would work, but if it's a script I'll have it running at all times. In other words, I'll be using this every logic tic so it needs to be efficient. Thanks.

EDIT: I've figured out how to find velocity on my own, but how would I use that xyz info to find speed?
Keep track of the objects previous position. Algorithm:

on each logic tick:
     speed_vector = current_position - previous_position
     speed = speed_vector.length()
     previous_position = current_position