I'm in a group and I posted something. Then, beneath my post it says "seen by 2" and when I click it, two users names are displayed.
1 Answer
It shows you how many people have seen/read it and (via the link) who they are.
It's a recent change (as of 28th August 2012) that's just been announced.
Here's a Techcrunch article that explains it in more detail.
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This is sort of a silly feature. It sounds like it still counts if a post is at the bottom of a page, and people normally only read new posts towards the top. Aug 28, 2012 at 18:45