'Any one of them could be right’
Even
Nate Silver, who thinks Coakley will probably win, is cautious due to the confusing signals from the polls:
This probably won't be a very satisfying answer to those of you who come to me looking for some kind of certitude. But part of being a good forecaster is knowing when to make a bold forecast and knowing when to proceed with more caution; the Massachusetts race calls for a heavy dose of the latter.
Update -- Reader AM:
But at least, in a one-race special election, there's no need to worry about how the undecideds will break. As we saw in the primary, they won't turn out.