I am one of those who doubted from the beginning that we had good reason to go into Iraq. I thought (and still think) that containment and inspections were working, and that there was no apparent connection to the Sept. 11 attacks. Having said that, we can NOT just walk out. President Bush's (and therefore, our) mistake going into Iraq will only be compounded if we just walk out.
Having said all of that, here's how I see it going forward. I don't believe there are any good options here, so we must choose the least bad option.
I believe we must choose sides in the current civil war in Iraq and help them defeat the other side. In our current referee role, we are backing a government that nobody there seems to really support. The Iraqi government is not collecting taxes, building infrastructure, delivering any services, or even providing the most basic protections of a credible fire or police service. Justice is currently being handed down by militias in most of the country - not any government system. So, in reality, there is no government. It's in name only. We need to pick a side that we can help WIN, even though it's not likely to be as democratic as we would like.
The only other option that would make sense is to partition the country - Kurdistan (US friendly), Sunni-stan (who knows?), Shi'a-stan (who knows?). Help them devise a way to share oil revenues and some critical natural resources and then leave them to their own devices - with a permanent US military base in Kurdistan, of course! (Sad, but probably necessary)
That's my two cents. I think we may see something pointing the administration in one of these directions in the next few months as a follow-up to whatever recommendation comes from the Baker commission. Seems like it could provide cover for Mr. Stay-the-Course to actually shift strategy and find a plausable way out.