Becky must be giving Greg a break, Two videos up in a day!
http://vimeo.com/14489187

Very cool...but check this link re: small hydro power.

http://www.canyonhydro.com/

Hydro is hands down the most cost effective renewable energy source. My own setup, (in addition to the wind turbine and solar/PV) uses 90 GPM, and has a total fall of 140' or so in about 1/4 mile. This turns my Idaho Power meter back @ 600+ watts 24/7 (unlike wind or solar) from very early spring until very late fall. Winter it is shut down, not worth trying to freezeproof. Fun stuff!

Small privateer hydro power is nothing new. My cousin set one up probably 30 plus years ago. Dammed the small feeder creek that run through his property and piped domestic water off it, as well as a pipeline down to a little powerplant. Maybe 500 feet fall in 1/4 mile? Ran probably 3/4 of the year (creek dries way up in summertime). Pain in the ass having to go up and clean the screen at the dam, plus change nozzles at the powerplant for different flow rates, but it did generate power excess of his needs which went onto the grid.