There are new Grips in AutoCAD 2011 that will allow us to modify objects with little effort.
2.) While you still have the Grip selected right click and take a look at the menu. There are several new Options such as Add Vertex that will allow you to add a point on the Polyline. Convert to Arc so you can change the Polyline to an Arc. See figure 2
Take a look at these new Grip options and I think you will be very impressed.
Thank you and happy gripping.