Nobody has posted any proof or positive rankings as a result of the +1. They like to think so or hope so, but there is nothing that shows for sure that it does or does not. Until I see something, I can only hope google hasn't stooped that low yet. But, I wouldn't put it past them either.
Google can easily detect the paid +1 and natural +1 by the content and the rank of the website. So don't worry try to focus on your content, focus your audience.
It would be nice to hear Google's official answer on this... +1 button really isn't all that great compared to Like or Tweet because it's hard to actually see any benefits to yourself when you click the button...
Kindly note that +1 button is only for google account holders for now and it do effect the SERPs but in a different fashion. I will try to illustrate its working by an example. Lets say their are four friends connected with their google account. One friend of them +1 a webpage or search result now if any of the other 3 friends search for the same information than that webpage will rank high from them.
I don't know if they have actively integrated this into their algorithm yet, but I think that there is no question that google has been putting more weight on social now than ever before. They do use these plus ones to boost your own results when you are logged in though, I believe.
At this VERY early stage of the platform, it is impossible to tell how it will /if it is affecting SERP. Give it time...
The effects will be inevitable, if you guys thought of it, then maybe that is something that Google wants us to think. So it's time to start learning +1 as it evolves. I wouldn't agree it is useless, for those who think it is useless, you are the ones who will be useless in the future if you don't get ready to adapt.
Even if it does not affect standard SERP's, it WILL affect the SERP's for people who are logged in. This is the next progression of Googles social search thing - if you are logged into Google, and one of your friends +1'd a link, that link will show up higher in the SERP's for you. So... it's not just about +1's, people think of it as just a number you can manipulate. This key is having +1's from lots of different REAL people - THIS will help you rank better for people who are logged into Google.