Here's a diagram from 3Jack Top 50 instructor, James Marshall. It is showing how the launch angle will change with regards to where the ball is struck on the face of a driver.
Here's another diagram showing the impact point and how it affects the ball speed.
What's interesting is just how much the results change if one hits below the sweetspot. The issue is finding the sweetspot. I have been personally told that the sweet spot was more up towards the crown and a little towards the toe. Perhaps that was a bit of an erroneous concept because one could hit 1/2" above the center of the club and only lose 1 mph of ball speed, but add 2.5* of launch angle and perhaps that adds a little more distance to the shots.
For more of James Marshall's work, check out his Web site at www.jamesmarshallgolf.com.