To capitalize on the "Democratic Wave" of 2006 in 2008 will require real leadership on the part of the Democratic Party, in success in overcoming whatever obstacles the Republicans and their President place in their way. If the voters who swung this election for the Democrats are frustrated by what the Democrats are able to achieve, they could easily rally behind a moderate Republican presidental candidate and sweep the Republicans back into majorities on his or her coat-tails.
It's always hard work to win elections, and harder work to accomplish something significant once in office.
It's going to be very difficult to unravel the international mess that Bush and his cronies have gotten us into, and the domestic mess could be equally challenging.