Diego Zaks has published a short video interacting with LEAP Motion, Arduino and LEDs. He also added a detailed tutorial to get started.
Diego Zaks: Might not be the most complicated setup ever, but it was fun to learn.
Detailed tutorial and code here:
http://thesis.diegozaks.com/2013/09/30/finger-tracking-led-light-up-using-processing-arduino-leap/