Support for Mubarak aside, our military has played a large role in educating and training the Egyptian military. Now as Mubarak is on the verge of collapse, he is almost certainly trying to order the military to crack down. The Egyptian military has refused to turn its guns on the civilians (thus far).
It would be nice if not massacring civilians was a given, but we've seen that very thing happen time and time again in dictatorships. The professionalism of the Egyptian military reflects well on the US military and the excellent job it has done in training the leaders of Egypt's armies.
The real question is whether or not the civilian leadership will successfully push for free and fair elections. My suspicion is that President Obama will do the right thing and reject the installment of another strongman to replace Mubarak. The Egyptian people need to finally have a chance to attempt to build a democracy.