What basically happens is that, whenever you search for something in Google (more and more in the future), say about "Ubuntu Tablet" :) then unlike in the past, if one or few of your Google buddies have already recommended it using this "+1 button" feature, then the big G will change their search results listings for you and may/will include the most recommend link using information gathered using the "+1 button which resembles the preference of your friends.
Although Google only has the authority over user preference "gatherings" within their services such as Gmail chat-buddies, etc yet other anonymous "votes" will also be used. They said that they'll be implementing the "+1 button" slowly... as a result, it took almost three months to the blogger team to finally enable it in posts in Blogger platform.
|The "Button" in action!... :)|
To do that,
1. Log-in to your Blogger Account.
2. Go to your Blog and click "Design".
3. Find your "Blog Post" widget (as shown below), click on the "Edit" button and make sure you've "checked" the "Show Share Buttons". That's how you add 1+ button in Blogger!.
Oh, btw, while you're logged in, when you browse your own posts, the "+1 button" is automatically hidden form you, obviously :).