Gigantic caveat: My name is Tommy Griffith, I manage search engine optimization at PayPal, and I'm shamelessly plugging my online SEO training course ClickMinded. Everything I say has an outrageous bias towards SEO. Now, on with it!
I remember when Google+ first came out. There was an avalanche of reaction from my fellow SEO nerds and the social media community. There were lots of reactions all across the spectrum, from "OMG, G+ will kill Facebook!!!!!!!" to "Here comes Google Buzz 2.0 - #FAILTROCITY". People instantly said, that because it's a social network, this is clearly Google's attempt at a head-to-head showdown with Facebook.
Now that we are well past the launch of Google+, and the social network has started defining itself a bit, I've taken a dramatically different perspective on what Google+ actually is. This is primarily because of the roll-out of authorship markup.
What's authorship markup? Well, Google announced in June 2011 that they would attempt to attribute unique content to authors, regardless of where they write on the web. You can read the official party line at the Webmaster Central Blog: Authorship markup and web search, but essentially, Google+ has become the centralized place where your "authorship" will effectively reside.
For now, not all verticals have adopted this, but most of the big players in SEO have. I, being an SEO guy, work in an industry where we watch Google's moves more closely than a southern baptist chaperone at a middle school dance. It's fairly natural to see early adoption of new stuff like this, but other industries may not have noticed yet.
One of the nice bonuses of adding authorship markup to your site, is that you get your Google+ profile picture embedded in the search results of any content that you author: a testament to the idea that people will create higher quality content if their name (or picture) is attached to it.
Now I'm not saying you need to call Google+ a religious experience like Guy Kawasaki, but you need to stop comparing it to Facebook. Google+ is where you let your Internet persona reside. G+ is somewhere in between your weekend keg stand blackout pictures on Facebook and your buttoned-up, outrageously exaggerated LinkedIn profile. This has become very evident in the SEO community, and I can imagine the trend will continue. Whether or not Joe the Plumber will have authorship markup integrated on his site by 2015 is outside of my prediction range, but this much is true: savvier verticals with an increasing reliance on Internet marketing are going to adopt this, because they'll have to if they want to stay current.
So... why? Why is Google doing this? Well, in my opinion, more and more people are becoming authors. Google likes credibility and accountability, but also realizes that the future of the Internet is not going to be individual webmasters posting exclusively on their own individual websites. Authorship markup is a great answer to this: a consolidated place where your authorship can follow you around the web to different sites, bringing along with it, your previous credibility. This provides more accountability and reliability to content on the web, something Google likes very much.
So, who's winning the social media battle, Google+ or Facebook? Meh. That's the wrong question. Google is carving out a very different kind of niche. One that's more closely associated with establishing strong connections between authors and their content. This is not the walled garden offline friend network you're used to, where people post passive-aggressive status updates about ex-girlfriends and check-in at trendy dive bars. What we are dealing with here, is a place where your unique online authorship profile can reside.
If you want to add authorship markup to your site, I wrote a quick walkthrough on how to do it: Get on Google+ (Authorship Markup Now Matters!), and if you're launching a new website, I wrote up an SEO Checklist for everything you should cover prior to going live.