In the last election, you may recall, the FL voter rolls were run through a process to remove felons -- or rather, voters who had the same name (or a similar one) and address (or anywhere within a few blocks, and including past addresses that the felon was known not to live at anymore). This naturally tends to take off a lot of people who have common names and live in predominantly black neighborhoods. These people were not informed they'd been de-registered. The number of people so affected was much larger than Bush's margin of victory in the state -- possibly into the tens of thousands. The company that did the scrubbing was a large Republican donor. And they're basically doing the same stuff all over again.
Incidentally, while I'm on the topic of voting, I'm registering for an absentee ballot. Unless you trust a voting machine company with a track record for suspicious bugs (like, counting more Republican votes in some heavily-Democratic districts than the total number of people who live there), I suggest you do so too, especially if you live in a contested state. (I'm mostly doing this to protest the continued use of the machines without open-source integrity checks and printed receipts; I don't think they could seriously get away with the level of tampering they'd have to use to swing CA.) If you're Californian, you can get a PDF of the relevant form by going to this page, or by directly downloading from this link. The counties also provide absentee voting stuff -- given that the forms downloadable from the state site are kinda messed up, I'd recommend going this route. See, for example, the Santa Clara, San Mateo, San Francisco, and Alameda sites.