OpenID is......ahem.....extremely similar to the (failing) Microsoft Passport system. The idea is that you should only have one login for all services offered on the internet (often referred to as "single sign-on"). The big difference (did i say big? i meant freakin' huge.) between the Passport system that Microsoft once trumpeted and OpenID is that OpenID is......anyone, anyone? Open. I've been reading a lot recently about OpenID and it seems to be picking up steam. The largest consumer issue with this type of system is critical mass. If no one has an OpenID then why would sites work to integrate it into their login systems? If sites do not integrate OpenID into their login systems then why would anyone sign up for an OpenID? You see the catch.
Background on OpenID: Can It Become The Preferred Single Sign-On System?