Yes, I am aware of the general rule of thumb which says that a refi makes sense when you achieve a 1.5 - 2 percentage points in your current vs. new rate (depending of course on any up front points or closing costs).

Now here's a question that I never see addressed. At the beginning of a loan the vast majority of each payment goes to interest but as time goes on more goes to principal. If a loan is running say 10 years a good portion of each payment is now going to principal. Even if the rates are 2 points lower after 10 years would it make sense to refi where you would pretty much be 'starting over' with large interest payments; therefore resulting in less of a principal reduction with each payment?