I'm not signed in, and the server didn't seem to set any cookies..

Here's a plaintext copy: http://cr6nh1.pen.io (though the formatting might be better suited to pastebin)

To counter what others are saying, I was being asked to sign in to view this article.

(Though as @chc points out < http://news.ycombinator.com/item?id=3384888 > I am signed into another Google property on my work email account, so perhaps that's why it's asking me )

i am not signed it, and I still read the article. I keep hearing this complain all the time with google groups. Is it specific to only few or are they based on assumption that it's a google group?

It's a weird bug with Google Groups. As far as I can tell, if you aren't signed into any Google service at the time, it will let you in. But if you are signed into another Google service, Groups will demand you re-authenticate.

Groups doesn't track which articles you read, even if you're signed in.