Take a look amazing presentation given by Sxip CEO Dick Hardt about Identity 2.0. Even if you are not interested about subject it self it’s really worth of checking out presentation because this 15 minutes video is made very well.
I like the concept behind Identity 2.0. Identity 2.0 is user-centric web identity system designed for next generation web sites. The idea is a single sign-on (SSO) system that, unlike systems like Passport, puts you in control of which companies host your data. Where basically you as a user control who can use your identity. For example you have login to Amazon, eBay, Slashdot, online banking, about 10 different forums etc. In Identity 2.0 you can tell Amazon to let authenticate you in Slashdot.