I, like Digby, am amazed that this article hasn't gotten more play.
When you're registered to vote, your place of residence is part of your registration. That tells the system what district you live in, etc.
However, when you're a beleaguered family in foreclosure whose house is gone and now you're living in an apartment across a county line, or with your mother in the next state, or something, probably updating your voter registration isn't the first thing on your mind.
These circumstances, in addition to the new, more stringent voter ID laws coming into effect in some states (Indiana the most recent and most prominent)--that is to say, what kind of identification you have to have on you in order to be allowed to vote--set us up for a whole lotta disenfranchised voters. Ballots will not be counted, votes will not be allowed, special ballots will get clogged in the system, and there will be mass chaos.
Note that these issues are particularly paramount in swing states. Economically (foreclosures), that's an unfortuate coincidence. Legally (voter ID laws), it smells pretty fishy to me. (Not to mention that voter ID laws disproportionately affect the poor, the less educated, people of color, etc.)
This is also part of the same meme as the right wingers trying to say that Obama's popularity makes him a fascist. Basically, since nobody wants to vote for the Republicans, they're trying to a) keep people from voting and b) imply that having people want to vote for you makes you Hitler (who is foreign, just like that black-Muslim-African-tooEuropean-latte-sipper of a Democrat), so vote reluctantly for the other (white, familiar, unfascistly unpopular--he's a Maverick, remember?) guy and be a Real American (TM) .