This is great thing for almost anyone who relies on their computer for a living, when everything has to be running all of the time, a power failure can really do your business some harm. But if this managed to reach the market at a reasonable price then everyone would be wanting one.
This UltraCell XX25 has been running constantly for four hundred hours because the device uses fuel cell technology it works the same as a battery, but without running down so long as there is fuel available. In this case it uses methanol and water.
Prices at the moment start at $2,500
Source [Next Energy News]