A typical AC compressor unit has a design life around 15 years or more; so, saving 30% of operating costs every year should result in a decent paypack. The Ice Energy website has cool schematics and install pics which TreeHugger recommends you check out before commenting.
From the Victorville CA Daily Press of July 26th. "Officials at Victorville City Hall are running one of Ice Energy's cooling units as part of a free demonstration project. After about three months, the city will look at the energy savings and may order three to four units for city buildings, said Jon Gargan, Victorville's director of community services"..."The city of Anaheim is also participating in the pilot project".
"The Ice Energy device includes a storage unit containing water is attached to the air conditioner. During the night, when the air conditioner is working most efficiently, the water is frozen. Then during the day, that ice provides a cool environment for the air conditioner to transfer heat from the building, increasing the efficiency of the air conditioner during hot hours, when demand for electricity peaks".
Look...over there...there's more good stuff just around the corner.