Last year, Nate Silver constructed a regression model which projected the date when a state's voters would vote against ballot measures banning gay marriage. In general, the model showed that opposition to same-sex marriage bans increased two percent per year. According to the formula, the magic number for Wisconsin voters is 2012.
To be clear, voting against bans is not the same as voting to establish marriage equality. However, as you can imagine, the two strongly correlate. If most Wisconsin voters would vote against marriage discrimination in 2012, it is, at most, only a few years until a majority will support establishing marriage rights for the state's gay couples.
The election results last week signal that Wisconsin's inevitable enactment of gay marriage will come a little later than it could have. The state constitution requires constitutional amendments to pass both houses of the legislature in two consecutive sessions. For the Democrats to regain both houses in 2012 is possible, but not likely. Somewhat ironically, in 2006 they took back the Senate and came close in the Assembly in part because of the youth turnout the marriage ban on the ballot motivated.
In related news, Cindy McCain appears in a video against gay bullying. In it, she denounces some of the policies her husband supports, including Don't Ask, Don't Tell.