I made this script that calculates the average curvature on a vertex and then puts the data into vertex colors. If you have any suggestions, comments or bug reports, please send a message.
You can make separate concavity or convexity maps and bake them if you want, or combine them into one.
The addon creates “Curvature” vertex color entry if it doesn’t exist and uses that to save the data. To see and test the vertex colors, it’s good to create a shadeless material with vertex color paint turned on.