As an aerospace engineer I agree with Husker Fan.
A golf ball's dimples work like the vortex generators you can find on the upper surface of some aircraft's wings: they delay the separation of the boundary layer. On a wing the purpose is to maintain the lift or to keep the rudders effective. On a golf ball the purpose is to reduce the area of low pressure in the ball's wake (F_drag = delta_p * A). 'A' is smaller the later the boundary layer separates from the golf ball's surface.
Similar approaches for similar problem:
- boat tails on bullets
- necking the rear end of cars (CRX, Prius, Audi A2,...)
Different approach for similar problem:
- base bleed artillery shells: reduce the pressure difference
