I'd say the same goes for internal corporate communications messages. And I'm not talking about emailing the entire organization.
For many of our customers, Jive has become that place. Jive communities are often the single place where employees go, not only to get work done or find experts-- some call this employee-to-employee interaction--but also to stay connected to the company, or business-to-employee interaction. And that's because their Internal Communications team knows to put their messages where people are already hanging out.
Heck, Jive has become the entire intranet in some corporations!