Andy Dale nails it when discussing the difference between SAML and OpenID. Why is OpenID getting uptake and SAML is being ignored in the web 2.0 environment:
I imaging a perfectly planned city… you bring together the best minds in social and urban planning and have them design and build the perfect city. Then you ask people to move to it… it’s big and empty and impersonal, its very perfection is off putting and intimidating. Meanwhile, just down the street there is a collection of mud huts with lots of people milling about, drinking beer and having fun. People are flocking to the village and it’s growing rapidly. The urban planners that built the city say; but don’t you see, you will need all the infrastructure that we have built in order to continue to thrive as a community, you’ll need police, medical and fire services, you’ll need schools and water pumping stations. But still people flock to the village to be part of growing something new and exciting. The villagers say; if we need police, someone will step up and become a police man, if there’s a fire we’ll get together and put it out. The inevitable outcome of the growth of the village seems to be a less well planned version of the planned city. It will, by inevitability, have many of the same features, some less well executed and some surprisingly better than the planned city.
To me, and maybe it’s just me, I know I would much rather be part of the village than move into the city.