Thanks for sharing this important petition, which I signed.
It petitions Navanethem Pillay, the UN High Commissioner for Human Rights, to "Amend Articles 13 (b), 55 (c) & 76 (c) of the 'Charter of the United Nations and Statute of the International Court of Justice,' to include freedom from religion." The current language in those articles of the Charter says "without distinction as to race, sex, language, or religion."
I signed it. I used to get things like this from Change org. pretty often but I think their budget is larger now.
The petition has been updated: it now addresses the new UN High Commissioner for Human Rights, Zeid Ra'ad Al Hussein, a prince of Jordan and a Muslim.
The sponsoring group is now known as Human Rights for Atheists, Agnostics, and Secularists. They have some rather upsetting news items at http://blasphemylaws.net/ (which redirects to http://humanrightsforaas.org/ ) .
Something to note: change.org is actually a for-profit company with incentive to get people to sign petitions, that gathers email addresses for organizations and accepts payments to promote petitions "related" to what people have signed. They've been criticized of "hiding" their for-profit status behind a .org domain (then again, look at craigslist.org), and they've been accused of selling your information to third parties.
I still sign such petitions -- I use a secondary email address that also gets "bacon" from political, social action, and other groups.