The other day I visited a friend who recently got a Labrador puppy, Mosè. He is now 5 months old. My God...he was crazy, he jumped all around the garded for thw whole time we were there. I tried to play with him but I couldn't...he just wanted to run and jump. My friend told me that he went into the house a couple of times, and in a matter of minutes it destryed a sofa and a carpet! It was pretty scary, for someone with the plan of owning a Lab :)
However, the next day I was in a bar and I met a man with a Lab who came in, sit down and had his Lab sit down near to him and stay calm until he finished the coofee. It looked like a different breed, really.
I think however it depends on the age. The first Lab was very very young, and at that age they just want to run a jump. Once grown up, I suppose they calm down a little, even if they remain very energic.