Of course, the Left, led by people like Andrew Sullivan, have tried to make it sound like the whole audience did.
Donald Douglas at American Power links to Sarah Rumph at Sunshine State Sarah, who was at the debate:
The debate included video questions that were submitted on YouTube, and one came from a soldier serving in Iraq who is gay and asked about the candidates' opinions on don't ask don't tell. There was audible booing after his question...however, please note that it was not the crowd booing. It was only one or two people.
I was at the debate, in the audience on the right hand side about halfway back (here's my tweet of the video screen that was right in front of us). The person who booed was just a few rows in front of us. The booing got an immediate and angry reaction from nearly everyone sitting around him, who hissed and shushed at him. Lots of loud gasps, "Shhhh!" "No!" "Shut up, you idiot!" etc.
Santorum didn't hear the boos and responded today.
More at Gay Patriot and This Ain't Hell.