Sadly, I have seen this kind of objectification of women in many science and engineering event in the past (not just in the US but Europe and Asia too). I have always been uncomfortable with it but it seems that many engineers do not mind... and perhaps secretly approve of it!
Re: "Is it because American football is so boring that it needs some real entertainment"
So...... If your statement/reasoning [hidden as a question] is correct, then the same must be true for DAC. You basically said 'use cheerleaders when the event itself is boring'.
"American football" is not boring - if you think it is, then you are probably just not capable of understanding it.
Do you think "American football" is the only sport that has cheerleaders?
If they are company employees who choose to dress like that and are not forced to, then there is nothing I can do about it. It is their personal choice. If they are hired to dress like that, then shame. Also if any company thinks it will make me look at their products more seriously, then they are badly mistaken.
Personally, I would side with Peggy on this one. While there is one context at a football game, it is not the case with most conferences - including DAC. University or high school cheerleading is one thing, it has become a sport with acrobatics and gymnastics (in fact, at C2MTL a couple of weeks ago, we had Cirque du Soleil do a brief number before Guy Laliberte's keynote). But this was the 49'ers, not Stanford (maybe featuring a cameo by John Hennessy?).