Great function. I was trying to do this for a bar chart, so it doesn't apply. Seems like it would be simple to adapt. However, I did notice that the function uses max(ytick) to calculate where to put the '//' on the upper x-axis. This may not work in cases where the maximum ytick is not on the upper y-axis. Perhaps use:
> v = axis;
> t2 = text(start+width/2,v(4),'//','fontsize',15);
10 Jun 2010
Inserts < // > into a 'broken' or discontinuous x-axis.