Great point Tom, and great handle.
While I've gotten a few leads from Facebook and Twitter, the true reason for my investing any time at all in those outlets is that potential customers often check these places to validate the popularity, or even the success of a business. If a fan page on Facebook has 4 likes, or a Twitter account has 17 followers, it's not a good signal to a potential customer, especially one researching web marketing providers.
The fact that Google now incorporates social metrics into their ranking algorithm also had some bearing on the energy and resources I've allocated to increase my company's presence on FB and Twitter.
The problem with Google+...
Nobody looks. Nobody cares. That's my experience.
I've invested a very little bit of time and money to add a few +1s to my website in order to increase the rankings, but that's it. I did see an improvement in rankings, and there wasn't much work involved at all, so I consider it a win.
The problem, in my opinion, is Google's almost Narcissistic approach to Google+. It's a Google product, so it matters. Why? Because Google says so.
I can't remember a platform that has had such little impact in the lives of real world users, yet such an effect on website rankings. Could be a good strategy on the part of Google, could fade away... we'll have to wait and see.