I've burning out the past 2 days trying to come with a recipe to get all the People who have +1 an URL, I'm trying to calculate the potential reach of a publication in Google+.
I did get the public shares of a URL using Ripple, amount and users, but is not the same.
I writing my app in ruby, but at this moment, I can't care less about the language.
To get clear view of my problem, please read my comment below.
There is no API method to get a list of who as +1'd a URL. If you would like to see such a feature please open a new issue.