Sen. McCain's pick should be as offensive to women as it is risky and questionable. What he's basically saying is: "Hillary voters, come over to my side because I've got a woman, and that's all that should matter."
It is degrading to all that female politicians like Sen. Clinton have done to this point, that Sen. McCain is banking on voters choosing a woman instead of her stance on the issues or experience, instead of a candidate who happens to have the stance on issues and experience which draws voters to a candidate who is a woman.
So, here's the difference on the issues between Clinton and Palin.
pro-LBGT rights anti-LBGT rights
Severely reduce subsidies for big oil in favor of subsidies
No drilling in ANWR Drill in ANWR now. (something McCain is even against...for now)
Radically Change No Child Left Behind Favors NCLB
opposes Bush economic policies supports Bush economic policies
Universal Health-care Competition based and less gov't regulations
wants creationism taught in public schools
decades of experience on a national level 2 years as governor