I’ve been banging on about Google+ for the last year or so and welcome Google+Communities which was added last week, as I think it is what was needed to make users become more active.
I see it as a great way  to build niche and focused communities applying the basic of community management. Google+ is already good for sourcing as it has 500 million users from this 135 million are considered active.

I personally see this replacing Google groups at some stage which even my son’s teacher uses to communicate with me via a daily update. I’m sure lots businesses will rush to open Communities as it’s a buzz word that is only growing. I would advise any businesses to think about a strategy before just doing it as it's new. There is no need to panic about vanity URLs; whether it’s public or private community the URLs are numbers only and don’t appear to be unique. The other factor you should consider is, do you have time to grow and moderate another channel? I see little point if it’s just going to be fairly inactive.

My two biggest likes are that you can create events and also have hangouts from within the community. Many of you will know that LinkedIn recently got rid of their events application so why not consider Google+ as a replacement? I would predict that in order to have success with this, it’s about building small niche communities and not to try and grow it to the numbers to some of the LinkedIn groups you have.

Some of the features included

• Public or private membership to support all kinds of groups—whether that be C++ developers or HR Managers
• Discussion categories to find the conversations you care about most
• The option to start hangouts and plan events with community members
• The ability to share with your community from any +1 button across the web

Two things to consider are once you’ve chosen public or private, that’s it – you can’t change it, so choose carefully. At the moment if you post on a public community that post will also be shown under your profile. If you are doing multiple posting in several communities, your profile could end up looking messy and like spam.

I think Google+ will add new features and also fix the bugs of the coming weeks. If Google do it in the right way they will beat LinkedIn on engagement. As the combination of Hangouts + Chat + Events - mean that the community experience will be far richer than LinkedIn groups.