Do NBA players make a higher percentage of 3-pointers from the side?

Corner threes are much more efficient than wing or straight-up threes. 82 Games' stats showed corner threes as being about 118.8 points per 100 possessions, while the other two are much lower. (Though, all three are worth doing - Wing 3s are just about the same as an average shot, and straight up (top of the circle) threes are 105.3 points per 100, which is quite good also. Only shots from the low paint - e.g., layups and dunks - are more efficient than those.)

Much of this is because these are more often uncontested shots made by three point specialists, of course; it's quite common to put a pure shooter (Kyle Korver type) in the corner and hit him with a pass when his defender comes over to the post to double someone. That means these shots are often unguarded, and so are higher percentage.

ShotTracker has a good writeup here too that points out the difference between a "pull-up 3" and a "catch and shoot 3"; corner 3s are usually catch-and-shoot (112 points per 100 possessions) versus 97 points per 100 possessions on pull-up threes [which, again, is still very good compared to any two point shot except at the hoop].

Finally, FiveThirtyEight has some nice charts from Kirk Goldberry, which I highly recommend.