Here's a link to a Youtube video that shows how to attach binding completely by machine "invisibly". (Think Harriet Hargrave's invisible machine applique.) She shows how to miter the corners.
http://www.youtube.com/watch?v=wprg5vzkuGw
In order to have machine binding look nice, I think you have to use either the invisible method above or use a decorative stitch. Basically you attach the binding to the back first, then turn to the front and finish with either invisible machine applique or a decorative stitch.