I Want a Gravity Powered Lamp

I want one of these:


"Gravia is an LED-lit floorlamp energized by people. To light Gravia, the user places a mass approximately 48" above the ground, that, in falling, powers a mechanism, generating electricity. Gravia harnesses the potential energy imparted by the user, rather than relying on any existing electrical infrastructure."

Update: This may not actually work. Damn :-(