I don't agree on that one. FB has been around for a time longer than Google +1. It wants to remain at the top. It won't do anything to harm its repo. I know the Google guys are ahead of their time but neither wants to copy the other. They are just trying of think of ways to stay at the top.
I just got a new option today on Facebook. When I tried to do a post on my facebook wall. Now we can put our location details with a post on facebook. I saw it first time with Google +1. So, facebook is trying to copy Google +1 This is proved.
Copying is never justified. "But as they say Everything is fair in love and war" this is war for both Facebook and Google. Until Facebook finds some serious claims for copying and decide to sue google we can't say anything as yet.
I beg the differ though. The whole social concept was popularized by Facebook. So far, Google is still behind Facebook in the social networking. For the copy, maybe you are right, but for all you know, facebook might have planned it before hand before Google launched it, like the video feature.