OpenID ??

today i read this article which explains what openid is ??

Lately OpenID has been hitting the front page of digg, del.icio.us, and many other large websites.

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OpenID - What is it, and why everyone is talking about it
you can also go through..
Authenticated Distributed Search (OpenSearch, OpenID)
Add OpenSearch to your site in five minutes

Additional link(offtopic and old article but i came across this well written article and couldn't resist posting it.. ):
What Every Webmaster and Web Developer MUST Know About Ruby on Rails and AJAX It’s not a tutorial, it’s not a “how-to” but he explains very well just what the heck all this.