I don't think any reasonable person doubts there would be sufficient evidence to at least get him impeached (remember, impeachment is Fed-speak for an indictment, not a determination of guilt). One commentator on NPR the other day pointed out that there would be at least as much evidence -- if not more -- against Cheney (sorry, no link, 'cause I can't remember who said it or when). There's certainly no lack of websites demanding Bush's removal from office (here, here, here, just to pick the first three from Googling "impeach bush").
No, if the decision were made to offer articles of impeachment, the problem would be knowing when "enough is enough". The boy has been so incredibly stupid, so amazingly arrogant, and so genuinely horrifying as preznit, we could probably come up with at least 500 articles -- each one a separate and discrete offense.
Badtux has pointed out that Speaker-Elect Nancy Pelosi has pretty much ruled out impeachment for reasons of simple math. The speaker is, of course, next in line after the Vice President.
More to the point -- as Badtux said at the end of his piece -- we'd wind up with (ulp) Preznit Cheney.
Now, I am hardly a Constitutional scholar, nor am I an attorney, but it seems there are a few different ways a possible impeachment ploy could work out. None of them are really good, at least from my point of view.
- Bush is impeached, tried, and removed from office. This leaves Cheney as president (someone shoot me). As we saw with the Nixon administration, the new president gets to name a new vice president. Cheney would probably nominate someone even worse than he is. We (as in the American people) lose.
- We impeach Cheney first; he's tried and removed. Bush gets to name Cheney's replacement. W would probably pardon Cheney (the way Ford pardoned Nixon) then re-nominate him. Otherwise, Bush would name some other moron -- like Santorum. We lose.
- We impeach Bush and Cheney together. If they're both removed from office, the presidency would land in Pelosi's lap.
This would be a win, except for one thing: I think a lot of people -- maybe even a majority -- would view it as a power grab by Democrats. It would be a safe bet that some Republicans who might vote to convict Bush and Cheney (Snowe, Collins, McCain come to mind) if there were a Republican Speaker, would not do so with a Democratic Speaker. So we go through all the aggravation of impeachment and a trial, and come out with... nothing. All we would have done is make both of them martyrs. Kinda like the way the Republicans made a martyr out of Bill Clinton.
I think (and I've said this before) we should let Bush serve out his term, go back to Crawdad in disgrace, and spend eternity being remembered as...
Worst. President. Ever.
At least Warren Harding would be happy.