In direct compitition with Facebook LIKE button, but with a even bigger impact, if executed as expected by Google.
Basically, Google will start showing this “+1” button for it’s adword ads, search results and eventually let websites/blogs add these “+1” buttons and help share/recommend good content to your friends or your “Social Circle“.
Source: Google Blog
If you are a webmaster and want to get invitation to get these +1 buttons for your site/blog, then signup for this newsletter from webmasters site.
Google Social Search helps you discover relevant content from your social connections, a set of your online friends and contacts. Content from your friends and acquaintances is sometimes more relevant and meaningful to you than content from any random person. For example, an online movie review is useful, but a movie review from your best friend can be even better.
Well, since this +1 signal will be one of the signal in determining the page rank or SERP position, some people will surely get prepared to trick it. Now have to wait and watch Google’s strategy to block it and give genuine search results and to be fair with the adword ads ranking.