These numbers are telling for me.
Number of Absentee Ballots Returned in Milwaukee County (a Democratic stronghold): 34,624
Number of Absentee Ballots Returned in Waukesha County (a Republican stronghold): 27,131
But Milwaukee County has roughly 2.5 times the population of Waukesha County. So what these numbers tell me is that Republicans are more enthused about voting (at least about voting early) than Democrats are, despite a well-publicized push by Democrats to get out their early vote.
Republicans are enthused by voting for Walker because they know he's right and they know he's doing the right things for Wisconsin. Democrats are disspirited for the same reason... it's tough to face that yoru sacred cows (collective bargaining, teachers' unions, public service) are actually bad for your community, when you've grown up as a liberal thinking they were noble and good. It's no wonder they're unhappy and unexcited about the election.
The same thing holds true for November. Republicans know that the ideas of Paul Ryan about the budget, about the Catholic Church regarding religious freedom, about conservatives regarding taxation and economic growth are right, and the liberal democratic shibboleths of unions and deficit spending and high taxation and government regulation are wrong. So we have the great energizing faith that we are on the side of the angels. Democrats know in their hearts that much of what they've believed in has been foolish, and, in particular, that the horse they've hitched their wagon too, Obama, is a nag, not a stud. So they're unhappy, and it will show up in November in lower turnout and a bigger than expected loss for Democrats (and what I hope and believe will be a relative landslide for Romney).