Smaller spaces, smaller children, smaller water bills--a toilet sink makes sense. Technically. But you can tell me all day long about how the water that comes out of my toilet tank is exactly the same as the water that comes out of my bathroom faucet and shower head, and my mind still won't be able to wrap itself around washing my hands in the vessel that eats my poo.
Maybe you're more rational, practical, mature than I am. If so, then by all means, crap and lather, dudes. Crap and lather.
Caroma's Smart Tank has a 1.28- / 0.8-gallon dual flush mechanism, and an integrated hand basin for further water savings. According to Caroma, "After flushing, fresh cold water is directed through the faucet for hand washing and drains into the tank to be used for the next flush."