According to Gallup editor Frank Newport:
I looked at the 8,700+ interviews conducted with registered voters in the month of September. I found that 41% of men were very enthusiastic about voting in the midterm elections, compared with 28% of women. That’s a 13-percentage-point gender gap. This actually represents a modest increase of enthusiasm among men compared with June, when we measured 36% male enthusiasm. Women have stayed virtually the same across time, 27% very enthusiastic then, 28% now. Thus, the gender gap has enlarged modestly.
The enthusiasm gap is particularly large among Republicans. Keep in mind that Republicans of most races, creeds, and ages are more enthusiastic than their counterparts who are Democrats. And keep in mind that enthusiasm among all Republicans has risen since June.
But Republican males are particularly more enthusiastic compared to Republican females. At this point in time (that is, September 2010) 56% of male Republicans are very enthusiastic about voting in the midterm elections, contrasted with 41% of female Republicans.
Compare that to the tepid levels of enthusiasm among Democrats in September. Here are the numbers: 32% enthusiasm among male Democrats, 25% among female Democrats. The gender gap is still there among Democrats, but more subdued than among the highly charged up Republicans. (There is a six-point gap among independents.)