I run my tyres on my focus at 50 psi hot with the TPMS showing tyre pressures and temperatures.
Wear is very low and is even due to less tyre heat than when lower inflated. The more a tyre flexes the more it heats up and the more it wears. Its actually a myth (from crossply days) that a tyre will 'crown' in the middle at high pressures. It actually stays flat due to the radial belts holding it in shape..... like its supposed to!
Run the tyres at the max sidewall pressure (either 44 or 50 psi) checked when hot.
Ride will be a bit rougher, and handling will be slightly worse, but rolling resistance will be much lower. Puncture susceptibility is slightly increased, but in most cases if you drive over a sharp object its unlikely that the tyre will conform around it, so you would probably have got a puncture anyway.
If you really want to lower the rolling resistance to next to nothing then fit the new Michelin Energy Saver tyres and inflate to the max sidewall pressure (51psi IIRC). You'll see a difference!
The official line from tyre companies is that they do not have data to support or condemn this practice as they don't test tyres at the max sidewall in real world conditions...... but the max sidewall pressure is there as the pressure to use at the tyre's max safe load (weight) at the rated speed, so if its at this pressure with a lower load then it can only be safer
For more info on hyperinflating tyres then see http://ecomodder.com/forum/showthread.php/hyperinflating-tires-2582.html