As of today, Google doesn't have a social platform to leverage +1. Without it, your upvotes are effectively going into a blackhole. Nobody will see them, so what's the point of upvoting and putting the button on your site?
But this is the creation of a social platform. They've just turned their search results, one of the most used things on the web, into a place where you will now see recommendations from friends if you search for topics where they've already +1'd it. It creates pretty much the same value as a Facebook like. You and I may dislike it and it does cause clutter, but Facebook likes are very popular with users and drive a lot of traffic. Google is doing the same on what I believe is a larger group of people and what I know is giving much more relevant information (i.e., I don't get informed about my friends' opinion on sneakers until I actively look for sneakers).
If I understood the article correctly, that isn't true. According to Google, your friends/contacts will see your +1s in their search results, meaning they'll have an additional hint at choosing the best result for them.
