The Senate's longest serving member, Robert Byrd, died this morning at the age of 92. This really isn't a big shocker. Byrd's health has been deteriorating for years and given his age, it was pretty much expected that this was coming after the news of his serious condition yesterday.
As far as a replacement for Byrd, well Nate Silver points out the timing on this. It looks like there will be a special election. If Byrd would have held on one more week, then the governor would have been able to appoint a replacement.
And then there's the big question - the fate of financial reform. That's pretty much uncertain now that the Democrats have one less vote. My guess is that it will be gutted even further to bring on Snowe or Collins.