Here's a blog post that explains the differences between bias and straight of grain binding:
http://www.jaybirdquilts.com/2011/01...cs-part-1.html
and here's part 2 where she shows how to make bias binding:
http://www.jaybirdquilts.com/2011/02...rt-2-bias.html
I am going to try making my next quilt with rounded corners and use bias binding. I don't really like mitering corners.