It all depends on the research group... I see a lot of activity on Facebook when an interesting paper comes out. Also <a href="https:&#x2F;&#x2F;www.researchgate.net&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.researchgate.net&#x2F;</a> is quite popular, but mostly for pre-publication discussions. The whole <a href="http:&#x2F;&#x2F;arxiv.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;arxiv.org&#x2F;</a> system is designed to stimulate discussion before a paper is published.