Facebook is currently testing mobile and desktop ads in Facebook Groups in Australia, Canada, Ireland and New Zealand.
Groups, which are used by over a billion users, is a popular feature that allows people with common interests and causes to come together to discuss issues and share content. With ad load for the News Feed expected to max out in 2017, this is being explored by Facebook as a way to continue revenue growth.
This update offers an opportunity to effectively target customers based on interest and group topic. But this is a test and there is no guarantee that this will result in a global roll-out.
Read more here.