Guy Kawasaki ha una teoria.
Businesses should jump on Google+ because it's the Wild West, so you can stake your claim, as opposed to breaking through the noise on Twitter and Facebook.
Also, Google owns the river called search traffic. It can point this river any way that it wants.
When Google introduced the concept of "social search," it turned SEO upside down. Now when people search on Google, they see the actions of their friends on Google+. That’s huge.