Nah, I wouldn't be too sure about it. They haven't even kill Facebook or Twitter yet.
Groupon doesn't have network effects to protect it.
They didn't clone Facebook or Twitter?
I thought that was the point of Orkut and Buzz.
Orkut may not have predated Facebook, but it predated the wide spread of Facebook--as I recall, I was able to use Orkut before Facebook expanded to my college.
FWIW I was introduced to Groupon by two people far removed from of tech circles. When I first tried it, it didn't even really occur to me that I was looking at a hot startup. I think its mindshare is plenty good among non-tech people in urban areas.
I would say Groupon is better known outside of tech circles than in. Most non-techies I talk to say "Oh, Groupon, it's so great and I love it!" Most techies say something like "Meh, nothing innovative, no defenses, it's a fad."
[Disclaimer: I work for Groupon and live in Chicago]
I live in Canada and none of my friends heard of Groupon.