I can understand what you all are saying here, but I don't necessarily think Babs was "wrong" in what she said. I believe that she said “muscle weighs more than fat” and that is true. I didn't recall seeing her write that "a pound of muscle weighs more than a pound of fat." Commons sense tells us that’s not true.
A followup to Babs original post stated that muscle is more dense than fat - that is true as well. If you're talking about having the same amount of muscle and fat (volume wise), then YES, the muscle weighs more… just by the laws of physics and the definition of density. Density = Mass/Volume. Since muscle is more dense than fat, it has a greater mass when compared to the same volume of fat. To me, that means it weighs more.
The nice thing is that, as Esteveze stated, it takes less space to carry a pound of muscle than a pound of fat! And it looks good too. ;-)