A nice compilation of Tim Lincecum related clips for your viewing pleasure.
I really like the comparison between Lincecum and cricket bowler Shoaib Akhtar, who at one point held the world record for fastest cricket ball in the world (100.2 mph). Both Lincecum and Akhtar use "momentum pitching", which helps them attain maximum velocity by creating a significant amount of forward momentum with their bodies, which is then transferred to the ball via their arms.
In contrast to the momentum approach, here's a clip of Felix Hernandez, who actually comes to a complete stop in his motion before throwing to home plate.
I'm not an expert when it comes to pitching mechanics, but I would much rather see a pitcher use their whole body like Lincecum than to use the stop-and-start motion that Hernandez uses. It seems to me that by utilizing your body more, it reduces the overall stress on your arm, and increases velocity without increasing fatigue. There's a really good article at Drive Line Mechanics about Hernandez and the whole momentum versus stop-and-start pitching approach.
Daisuke Matsuzaka seems to have a mixed approach, creating some momentum, but not quite as much as Lincecum.
This final clip is of Greg Maddux during a bullpen session. He uses a very smooth momentum based approach that allows him to create velocity without putting much strain on his arm, and allows for a very efficient approach.
Everybody's different, so it's impossible to say that one approach is always better than another, but I think I prefer the momentum based mechanical approach.