The really simple way to do it is to just grab the bar with the mouse and move it. Do you want to automate this?
If you do want to automate it, you can play around with the properties of the graphics handles. Here is an example where I create the colorbar for subplot 1 and move it to subplot 2:
h1 = subplot(121);
surf(peaks(30));
cbar_axes = colorbar;
h2 = subplot(122);
%Get the relative positions of the two subplots and use to adjust colorbar position
v1 = get(h1,'OuterPosition');
v2 = get(h2,'OuterPosition');
va = get(cbar_axes,'OuterPosition');
set(cbar_axes,'OuterPosition',va+v2-v1)
axis off
