I worked in electoral politics for more than 5 years and sometimes you can feel the wind blowing one way or the other and this year's breeze feels like a Democrat storm.
Dems have already won special elections this year in heavily Republican congressional districts in Illinois and Mississippi. They are leading in several Senate races that pundits predicted should have been safe = Democrat Tsunami.
Dems could win another 20 House seats and 5 or more Senate seats. Obama also obviously starts with a huge monetary advantage over McCain.
My only problem with any of this is that we are only one Supreme Court Justice away from overturning Roe v. Wade, which would return the decision to the individual states and would stop abortions in at least a dozen states which would save thousands, if not tens of thousands of lives. Constitutionally, it would return the issue to the states where the Founders left it at the beginning of the Republic (yes, they knew about abortion).
Before you vote this year, do yourself a favor and rent the documentary Unborn in the USA, an even handed look at the abortion debate. If you have a subscription to Netflix (and I recommend that as well) then you can watch it instantly on-line.