The second problem is based on the idea:
"Why are you on Facebook".
You are on facebook, because your friends are, so you can communicate with them and know their lives. Ok
Now, take Google+, a new social network. Even if you go there, your friends will not be there, why, because first, they are not IT people (so, they will not try the last new thing out) and secondly because they don't see why to change (Facebook is ok for them).
So, Google+ will have a hard start, but it has also a high level to fail.
In fact, the problem is the same, with Instant Messaging (IM). You are on MSN to talk with your european friends. On Skype for others, and GTalk for some geeks. If you would like to move from Skype to something more open / less black box, you can't since your friends will not follow, and since they don't really care about all your crap Linux stuff
