Will the United States ever again be generally unified politically?

With so many close presidential elections (2000, 2004, and apparently again in 2008) have been decided over wildly differing platforms, I wonder if this apparent discord will ever be resolved. Is it possible that Americans could reject the two parties in power and favor some non-Republican/non-Democratic one? Can unity occur in Congress and among the people even with bipartisan politics on the table? Will we forever have this liberal/conservative distinction in our society?