KE7GKP:
Arduino is barely capable of tracking a well-contrasted spot on just one camera.
If you need multiple cameras, then you need to aim higher than Arduino.
Not necessarily; while not quite the same as what the OP wants to do, the following was done as an early motion tracking experiment, which was called the "Twinkle Box" - you can download a copy of the paper here at my website:
http://www.phoenixgarage.org/show_article/113
This was done circa 1974 - I'm sure the Arduino could handle a similar system...
