Disqus seems increasingly popular for comments on website blogs. It is impressive what a good job it does integrating with Facebook, Twitter, et al.
For those that are f
Disqus via the Universal API allows for you to create categories, threads and post structure which is basically your typical forum layout. Most of the API methods have a beta label on them. Check it out here: http://disqus.com/api/docs/
To answer your question - Yes it's possible to develop your own forum solution using disqus API - Just requires a lot of backend work on your part as a developer.