I am following a site that is on the first position in the serps for a few competitive keywords. The strange thing is that more than 3000 people +1'd this site and that might be one of the reasons why it is doing so well.
I thought that only a few people were using Google+. The website is mainly visited by women and teenage girls. I would be surprised if so many would +1 the homepage. Or are they using some method which adds up all the +1's of the internal pages?