Is it possible to estimate airspeed on top and bottom sides of a wing at zero angle of attack?
The short answer is that it is possible, by way of knowing the pressure distribution and applying the Bernoulli equation to relate the pressure and the velocity. 

More specifically to your question, I'm not aware of any published correlation between camber and air velocity (nor do I think it'd have much practical application), but you could come up with your own by running a variety of geometries through XFOIL for a given airfoil geometry (maybe a Clark Y of varying camber for a flat-bottomed design) and applying Bernoulli on the calculated pressure distribution for whatever freestream atmospheric conditions and chord length you want.

Another note: You asked specifically about a wing, not an airfoil. A wing will have lots of other effects contributing to variations in velocity over its surface; there is no easy way to account for all of them.