On top of adding their voice to discussions, users will also be able upload their images and start new conversations. Like or hate something someone said? Just up or down vote it. 500px also says its working on adding more features soon including group creation, whereas currently community members can only join groups 500px has made itself.
To join the conversation users simply need visit the 500px Groups beta page. While 500px is just adding discussions now, Flickr has had them for quite some time, but it never hurts to conversate in even more place about photography.