O Caos é Eletrônico, I think you read about the concept of @mentions and stopped there. If you re-read it, you’ll hopefully see the MUCH broader underlying point.
I’m aware that one can do @mentions within Disqus, but they’re limited to activity within Disqus itself. This is the same thing as @mentions on Twitter only working within Twitter.
What I’m suggesting above is that they support a broader open spec that allows @mentions between other services. So, for example, I could @mention someone on Disqus from Twitter and potentially vice versa. If you can only have conversations with people on Disqus, you’re limited by how big and popular Disqus is. If you can @mention people outside of the Disqus echosystem, the product becomes that much more powerful!
Imagine if every blog on the planet could @mention every other website, or even Twitter or Facebook users across platforms? Why should you rely on everyone being on the same platform to be able to communicate with them?