And don't forget Google Wave that did the whole "chat integrated with various multimedia elements" decade before the competition (and arguably, better, coz those could be interactive elements not previews of websites and embedded media)
> https://en.wikipedia.org/wiki/Google_Wave
Apparently it was generally available for 3 months. Probably why I missed it.
I didn't try Buzz either.
(there was a lot of other stuff going on in there too)