I think this could be the moment we've been waiting for. Bush's crimes have always been a little murky to most people prior to this--there hasn't been the kind of smoking gun (blue dress) that's needed to get the American people's attention. Most people need very simple proof, and they're not necessarily paying enough attention to connect the dots like we are.
However, this is a crime that we can convince the American people about. This is very simple:
Bush commuted Libby's sentence as a reward Libby for obstructing justice to protect other top Bush administration officials from an investigation, possibly including Bush himself. This is an inexcusable conflict of interest.
Bush just sent the message that his top officials are above the law--they can obstruct investigations with impunity now. If you're high up in the Bush administration, if you shield Bush, he'll protect you.
Bush's move is utterly lawless--it's his statement that his people are above the law. You let Bush violate the law, he'll let you violate the law. It's that simple.
The sound bite version: Bush rewarded Libby for covering up what could be Bush's own crimes.
I think this is enough for impeachment--this is a high crime in my book, and I think we may be able to convince people of it.