TopTechNews has an interesting article about how or IF Google+ will be a direct competitor to the likes of IBM Connections, Microsoft SharePoint and Jive. They make some decent points but I think for true enterprises it will little affect unless there is a push to take non-mission critical applications off-premise and they are reviewing cloud or hosted solutions like LotusLive, Jive Hosted, Salesforce Chatter.
With that assumption, I really think the threat would be the likes of Chatter and possibly Jive. Many SMBs may already have Gmail for their email, IM and calendaring and as they grow or see opportunities for collaboration internally or externally Google+ could be an option. Many of these SMB’s have already moved their CRM to something like Salesforce as well. I specifically know of a friend’s company that is doing exactly that and when we talked last week he asked about Chatter and knowing his business it was a good opportunity. They were exploring re-expressing some internal applications on Force.com – it made sense. Today I would say that since they are already doing the most basic form of collaboration (email) with Google Apps maybe they should explore Google+ if it becomes available.
At the end of the day, Google+ needs to prove itself just like the “big boys” and given that it does its homework and builds out something that could be useful and meaningful. Collaboration isn’t being just tried out anymore, its a strategic initiative by some of the best and brightest companies on the planet – so they need to know that Google+ won’t just Buzz-off and be around for the long haul.