Inside the core - the dnn community edition has all the wiring to support any number of social interactions - but there are only a limited number of these social style features directly implemented out of the box.
One of the things to understand about the current version of dnn - unlike the past where when you installed you got a bag load of modules installed as well - these days when you do an install - all you really get is the CORE. And like most things DNN once you get above the core itself it it all comes down to what modules are available or can be sourced for the task you require.
Out of the box - dnn includes a native internal messaging and notification system - a new form of security roles - which directly maps to Social Groups - and a social newsfeed style social interaction system that can yes handle multiple social groups in a very facebook like social conversation timeline.
Yes this has some considerable basis in the Active Social module - but many would also argue - that what is implemented is not completely representative of what was available in active social - though on the other hand - there are some areas that have improved as well. As for active forums however - well thats not as a good a story - basically it was abandoned by dnn. It has since been picked up as a open source project - and there is a team working with it - but its relationship to the social elements now in the core are somewhat strained.
In terms of things like gamification/ratings etc and things like the Community Exchange/ Community Voice features you see here on the dnn site - well they are a little more problematic.
None of those sort of features are available out of the box - they are private modules that are only available completely for evoq social customers.
There is a open source project underway which is based on the Q&A module that the community exchange system was developed out of - which may give you some better understanding of what is doable with open source.
There are some external modules that are being actively developed in the 3rd party commercial space that interact directly with the dnn social stream system - have a look on the dnn store for those -
http://www.easydnnsolutions.com/Modul... for example.
And there are some free modules that are also still being developed - which are seeing some social elements being integrated - the media module springs to mind and the dnn events module also has been extended to allow the events module to be placed on a social group page - the dnnblog module is also still being actively developed.
One way that you may get a better idea of what can be down with open source modules is to have a look at
http://www.dnn-connect.org/ its a dnn site specifically focused on the community edition of dnn - and driven using open source modules.
Westa