The poll brittain33 was mentioning is now out; it's a poll just of Wisconsin, with the Rasmussen Likely Voter screen applied.
(link).
52-39 against weakening collective barganing rights
44-38 in favor of a 10% pay cut for all state workers
49% of voters, and 58% of those with children in the public school system, say it's a good thing that most teachers belong to a union.
Regarding this last statistic in particular, I do think that certain market-liberal type people, including some on this forum, not all of whom are fervent conservatives, are out of whack in their perceptions of how middle American parents see the teachers.