[Platapus]

Well before getting too excited about whether there will be 60 Democrats or no in the Senate, please remember that it takes 60 votes to invoke cloture in the Senate. Not 60 Democrats. Just 60 votes

Specifically, since 1975 three-fifths of those Senators "duly chosen and sworn"

All Democrats do not vote alike. There can be 60 Democrats in the Senate and they can still fail to invoke cloture if some of the Democrats disagree (Senators have a habit of doing that)

Likewise, if the Democrats do not have 60 members in the Senate, they still may be able to invoke cloture if some of the Republicans or Independents decide to vote in favour of cloture.

The fixation on the number 60 is sophistry as it presumes that all Senators always vote with their party all the time. And this just does not happen.

So the chances of the Democrats defeating a filibuster after Spector becomes a Democrat are pretty close to the chances the Democrats had of defeating a filibuster before Spector became a Democrat.

In the Senate there is no such thing as a "filibuster proof majority"

The best or worst that can be said is that party X is now more likely to be able to invoke cloture then they were before.