Here's a really good explanation of what that means, put together by ABC news. If you're not sure where your Senator stands on the issue, here's a handy site with that information (and more). At this point, petitions and postcards are not particularly helpful but calling your representatives is. Daily KOS has put together a list of phone numbers. Here it is. (And keep it handy because there's going to be a new vote on the evil tax plan pretty soon as well.)
