Has been said many times, but Google+ was hoping to be as good as Google Reader and Google Buzz already were for people. Was a surprisingly good social layer on top of article aggregation that largely worked by leveraging GMail.

What they were not, of course, was a replacement for the "town hall" dream of social capture that places like Facebook are hoping for.

And, I'm a bit hazy, but didn't Youtube try and force comments to be tied to your google identity?