I'm starting to find value in Google+. Rather than posting the typical FB garbage of what you had for lunch or that you just farted, people seem to have higher value content such as links to very interesting articles. Theres's less quantity of posts, but higher quality. I hope this continues. :-)
I could see G+ replacing the functionality in FB, Twitter and LinkedIn. But it still has a ways to go obviously before that happens. I would love it to incorporate Google Groups as well. Just create a new Private Circle as your group. Would be great for planning trips with friends or managing small off-site projects.