Paul Madsen points out an unflattering comparison between Facebook Connect and Microsoft Passport:
There is a lot to this comparison, but there is one important distinction. But first a disclosure; I have in the past developed implementations of SAML, Liberty, InformationCards, and WS-Federation specifications. I am a big fan of standards and open specifications. But I have also written integration code to authenticate using Microsoft Passport because I have to make a living.
The main distinction between the two is that there are a whole lot of people who don’t mind Facebook being in the middle. Microsoft never had a site that drew the kind of devotion levels that Facebook enjoys.
Will that ultimately make a difference and allow Facebook Connect to succeed where Passport failed? I’m not sure, but I wouldn’t bet against it.