I just travelled with AA 2/21/11 and could not believe how long it took to board and leave the plane.... I suspect this is an ongoing problem for many, if not all, airlines. There were countless passengers with oversized carry-ons (which should have been caught by the check-in agents) that cause the boarding and take-off of the plane to be delayed. Then, on a full flight (and most are) the overhead compartments become full very quickly with purses and coats and oversized carry-ons that barely fit, and then other people are forced to place their carry-ons below the plane. It's a huge problem and it's getting ridiculous.
Another thing, why is it that so many people refuse to place carry-ons below the seat in front of them?! And why do the flight attendants allow it?!