I personally run my tires a little lower than recomended. Front around 32 psi, rear around 36 psi. BUT, for makein trips, etc, you are better off with the higher pressure. It depends a lot on where you ride, the type of rideing you do, how agressive you are on the bike, and also the tires you have on your bike. I run Diablo Corsa's, and thoes pressures tend to work well for me. I am moderately agressive on the bike, and mostly just take the bike out for the twisties. I don't ride around town on it just for the sake of ridein the bike around.
We also have some fairly slick roads around here. LOTS of oil. A little extra contact patch isn't going to hurt your tires much. But, if you do run them lower than recomended, be sure and keep an eye on them, and check them often. Not much leeway between underinflated, and flat

Woulden't want anyone to think you are a stunter (Or worse yet, go and lay the bike over because a tire gave way. Or worse yet, have it explode on the highway because it got too hot from constantly flexing.)
Anyway's, I am by no means an expert. These are just the pressures I happen to run on my bike most of the time. (I have varied it up on Cali trips, and a lot on the track.)
- Ice_Hole