I wasn't playing the role of "investigative reporter" at dinner, so I didn't press here. One of the guesses I have is that the technology used for Disqus could be implemented across corporate intranets, white labeled and licensed?
Another approach: Fred Wilson's post today on comments constituting blog posts suggests that maybe they're building towards a sort of blogging platform for non-bloggers, where the aggregate of a user's comments on other blogs would form a new low-maintenance blog (on the Disqus site).
The point is that there are probably 10 active commentators for each active blogger. Perhaps Disqus is building towards a platform for people like this, who comment actively but who don't want or think they wouldn't be able to run their own blog.