Two posts on a similar theme today: at Greg's place I talked about three new Crossroads ad campaigns in Senate races, and my PP piece argued that we really don't have to worry too much about the new campaign finance regime and the White House (that is, outside spending is unlikely to be important in the presidential race), but the House is another story.
I should have specified: that's true both for overall control, and for individual seats.
What's interesting is that so far, as far as I know, virtually all of the big outside money seems to be partisan money. Now, that's not a huge surprise in a very partisan era, but it's still interesting. So far, we haven't had (against, as far as I know) any unaligned interest groups try to take out two or three prime targets -- or try to get themselves a Member of the House or (less likely) a Senator who will put their interests ahead of party. This may be because the current era encourages interest groups to align with parties, even at the cost of losing some freedom of action; it may be because it takes a while for groups to adjust to new incentives and institutional structures; or there may be some other reason. I'm a great believer in the notion that rules disruptions are bad for parties in the short term, but as far as I can see that doesn't seem to be the case with the changes in the campaign finance regime. Or perhaps that means that the change isn't really all that significant after all.
Obviously, that's all speculative. I'm also out of date on the campaign finance literature; I used to read it carefully, but not in the last few years, so perhaps some of this is answered out there.