Mick is right. Nancy et al. have to prove they are interested in co-operation, not gridlock--or they will be out on their ears in 2008.
Impeachment talk may make you feel good--but it won't happen. To impeach and convict you need quite a bit of Republican co-operation--which won't be there. And even with the recent attack of good sense on the part of the US voting public, the balance in the Senate is only 51-49. Not enough to impeach and convict.
And the US public is not interested in vindictive behavior on the part of newly resurgent Democrats--they'd rather get some problems solved.
However, as I've pointed out elsewhere, in-depth investigations can proceed--as for instance on the question of just how the propaganda campaign that got us into the Iraq war worked. And Cheney, for instance, is in that up to his neck--or above.
Specifically we need an inquiry into the contradictions between what the Bush regime was telling the country and what the intelligence community knew at the time.