1/2 support.
It would be nice to be able to edit polls... but only if there are zero votes. Once someone voted it should be unchangeable.
Otherwise editing polls would be abused. Like with the poll you have right now: you could change "yes" to "no" & "no" to "yes". Besides, even if it weren't abused think of this -- a bunch of people vote, then you add a new choice... results are kind of skewed now since the first people to vote didn't have that choice.