Google’s +1 is still relatively new and the impact on seo is still being monitored, looked at and watched by the seo nerds. It is also still being tweaked and in Google search the +1 button only shows up for signed –in Google users using a modern browser.
Google says that the +1 is to help people recommend articles, pages and content to other people. A friend recommending something to you is more relevant and personal to your taste and you’re more likely to follow up that recommendation than a recommendation from an expert that you don’t know.
The search impact section of the +1 metrics will let you see how exactly +1’s affect your site performance in search results.
This section shows you the number of times your pages have been +1’d by someone.
Who +1’d your pages, unique number of users, their location and rather scarily their age and gender too. (This info won’t show unless a minimum number of people have +1’d your content.
You might also like to read :
Site Configuration - read what the site configuration section covers.
Your Site on the Web - read about the Your Site on the Web section.
Diagnostics - Read what’s in the diagnostic section.
Labs - Google playground.