This effect was discovered long ago. But industry seems to have suddenly become aware of it only recently. This accounts for the sudden rash of cooler cabinets for soft drinks that suddenly appeared on the market a couple of years ago.
Reversing the voltage produces a heating effect. I'm told that the French are installing these Peltier devices in their homes as a type of air conditioning. Though they're not all that effective, they use little power.
There's more on the effect
here.