Matthew Yglesias takes note of these comments from Joe Biden:
"I know at least 7 [GOP] senators, who I will not name, but were made to make a commitment under threat of losing their chairmanships, if they did not support the leadership on every procedural vote," Biden said at a fundraiser Monday night.
"Every single thing we did, from the important to the not so important, required for the first time in modern American history, majority votes required 60 votes. All the sudden a majority became 60 instead of 50," the VP added, according to a pool report of the event.
Republicans object, but Biden's observation certainly seems to match up with observed reality. (For instance, Olympia Snowe voted for health care reform in the Senate Finance Committee, then voted to filibuster essentially the same bill. The latter was a procedural vote, the former wasn't.)
I think the best to this kind of behavior is to change the rules -- I find the theoretical defenses of the filibuster very weak, and even those don't account for anything like the minority party pledging to vote with the leadership anytime it chooses to filibuster. The second-best response is to mimic that behavior and pledge to support your party's leadership on every procedural vote. In essence, you'd be separating the vote to proceed from the substance of the issue. Moderates could vote no on the underlying bill any time they wanted -- the filibuster vote would stop being the story, and the vote on the bill itself would become the story, which would allow moderates to demonstrate much more independence from the party than they currently do.
The worst of all worlds is to have the other party unify on every procedural vote while your party does not. That's the Senate 2009-10. That reality has driven the legislative dynamic of Obama's crucial first two years.