How Did Obama Campaign?

We've heard for about two years now that Obama had campaigned in 2008 as a centrist.  So why is it now that the left is in a tizzy over supposedly broken promises, threatening a primary challenge? 

Gitmo, Iraq, Afghanistan, Single-payer health care, DADT, taxes...

So did Obama campaign on a lefty wet-dream list of promises?  Or did he, as the media has so dutifully reported, campaign as a centrist? 

It can't be both.

I think you know where I stand on that one.