rango - 4:07 am on Aug 24, 2012 (gmt 0)
They can and they already do
I'm specifically referring to the fact they could ignore them when calculating panda ranks, not to ignore them in the serps. The only real reason to noindex them is to avoid a penalty. But since they can so easily see it's an unanswered question - why would they bother counting it against you or showing it in the serps.
Stackoverflow is a good format for some types of questions - specifically ones where there is such a thing as a "best" answer.
In other fields, it's better to have discussions rather than a definitive answer imo.