If, for some reason, the most hysterical mainstream news media fantasies should come true, and the Republicans take control of both branches of Congress, the Tea Party nutters will not be running the show. The folks who will take real control of that branch of government--the Boehner/McConnell types--will hold real power. They probably will not pursue the nuttiest ideas that freshmen representatives and senators campaigned on, and most of the nuttiest are probably less nutty than they appear. Not all politicians are 100% honest about what they really intend to do, once they take office. At that point, the Republican political calculus will turn to what will win back the White House in 2012. If voters are stupid enough to elect nutty Congressional representatives and senators, then they probably won't be overly concerned that the nutters failed to carry out their agenda. So I expect the Republican leadership to resist shutting down the government over unpopular fringe ideas.
My most cynical assessment is that the Republicans sweep in with relatively large numbers. The next two years will basically get nothing done to solve any of our serious problems. In 2012, disgusted (but fairly stupid) American voters will once again do the same thing, expecting different results. They will throw out the (this time Republican) bums in Congress and elect a Democratic Congress with a Republican president. Whatever they do, they re-affirm George Bernard Shaw's cynical observation that democracy is a system of government by which people get a government no better than they deserve. :areyoucra