I've lived and worked in Northern Virginia--a bit closer in, around Fairfax, Clifton, and Falls Church--all my life. And I've volunteered in a number of presidential, senatorial, and congressional campaigns...so I do think I have some perspective on the impact of elections on regional house sales.
There will be some effect from the elections on house sales, though not a huge effect. First, as Cindy notes, some senators, congressmen, and staffers are permanent (or semi-permanent) residents of the area. Not all of them, of course. Some congressional staffers will go home. And certainly the newly elected senators and representatives will bring some staffers with them. The same applies to politically-connected positions within the Executive Branch--not just the White House but Cabinet-level departments, too. And that'll apply whether Obama or McCain wins. (More for Obama, but even a McCain election will result in many changes of personnel.)
Having said all that, what's the effect on the real estate market? At best, a slight to moderate effect in some of the closer-in areas--District of Columbia, Arlington, and some areas of Montgomery and Fairfax Counties. Farther out, such as in Prince William County, I see less of an effect. People who work for the Administration--or for representatives or senators--put in long days. They need to be available on short notice. And so Prince William County isn't at the top of most of their lists.
In short, I wouldn't look to the elections to spur a big surge in real estate activity. And November is somewhat late in the fall, anyhow.
The fall isn't a bad time to put your home on the market, though spring generally is better. I'd recommend making your decision without attempting to factor in any effect from the November elections. That effect will be minor at best, and at the far end of the fall real estate season.
Hope that helps.