In the U.S. Senate there are no hard limits on the length of debate on a bill. Senators can talk as long as they like, unless 60 out of 100 Senators vote to end debate. This allows 41 determined Senators to prevent a vote, thus preventing a bill from becoming law.
Before the 2007-2008 Congress the filibuster was rarely used, but when the Democrats won the 2006 congressional election, the Republicans started using the filibuster frequently to prevent bills from passing. Since Democrat Obama won the Presidency in 2008 and put together a 60 vote caucus in the Senate, Republicans have filibustered at an unprecedented rate so major bills can only pass if every single Democrat and Independent votes to end debate. This has significantly limited Congress' productivity. With the recent election of a 41st Republican Senator, the Republicans are in a position to prevent any bill they don't like from becoming law.
While the Republicans are definitely being obstructionist, preventing the majority from governing, the Senate leadership is making it easy for them. To prevent a vote, Republicans don't actually have to keep talking for hours or days, the Republican leadership just says they will filibuster and a 60 vote majority is required. Thus, filibustering is easy and cheap. A few words and it's done.
If the Democrats want to pass their agenda, they need to make filibustering costly, not cheap. This can be done in two ways: physically and politically.
Physically, the Democratic leadership can force the Republicans to actually filibuster, not just say they will. Make them actually stand up and talk for days. The rules say no sitting, no food, and no bathroom breaks. If they stop talking a vote can be taken. Even thought they can tag team, it's still painful and difficult.
Politically, filibusters can be made costly by broadcasting the debate on CSPAN and taking the best bits for YouTube. To talk for days you have to either repeat yourself endlessly or introduce irrelevant material, for example, reading the phone book. That won't look good on TV and can be incredibly useful in campaign ads.
If you think President Obama is intelligent and has the best interests of the country at heart, then help him get his middle-class-focussed agenda passed. Contact Harry Reid, the Senate Majority Leader, at http://reid.senate.gov/contact/ and tell him to make the Republicans actually filibuster, not just say they will.