One President was impeached against the will of the American people. The other has (so far) avoided impeachment despite the fact that most Americans favor impeachment.
As the sane republicans continue to wake up, I should think we'll see more "impeachment" stories over the next few months.
Right now, I'm on the fence about impeachment. Clearly Bush is a criminal. So I'm in favor of impeachment in order to defend the principle that no person is above the law, however I'm against impeachment for political strategy reasons.
Impeachment gives the wingnuts something to rally around, and the next democratic congress is going to have a hard enough time fixing everything that Bush has broken without adding impeachment to the mix.