Tucked into Zuckerberg's livestream today about Russia was the following:
(starts around 05:00 mark)
"Not only will you have to disclose which page paid for an ad, but we will also make it so that you can visit an advertisers page and see the ads that they are currently running to any audience on facebook"
FB creating their own ad spy tool? It was said in the context of political ads, but it sounds like it may apply to all ads.
Wow that's interesting and/or disturbing 
This was specifically for Political ads i guess