Having seen a lot of the content that goes through these products, from the compliance side, I'm not sure that they are particularly "productive." Where they have any uptake at all (surprisingly rare, for such expensive products, that require so much work to implement and roll out), it's pretty... meh.My feeling is that a lot of this is because people thought "Hey, we can make a private Facebook clone and drop it inside our organization and people will use it to be more productive". I think that's a mistaken approach. "Social" tools certainly can have value in an organisation, but there's nothing magic about a Facebook clone (or web-based IRC for that matter).
Our position at Fogbeam is that ESN's (Enterprise Social Network), in order to provide real value, have to do more. That is, they have to connect with the things and ways that people actually get work done, and make it easier to find (information|people|documents|whatever) that you need to do something... in addition to the fluffier "idle chit chat" aspects. If an ESN can do that, then it can provide value.
Of course, I'm biased, as that's one of the ways in which our ESN approach differs from some of the others. We have a tremendous focus on integration with other enterprise applications. And we use semantic web technology to do automatic semantic entity extraction from the text flowing around the system, so we can build a knowledge-base that helps people find related information.
I'll be the first to say that a lot of companies have not received as much value from deploying internal social software as they might have expected. We just think it's (in part) because they used first generation social software that doesn't provided the needed capabilities.
Another reason that companies fail to get a lot of value from this stuff is much harder to resolve: company culture and values. Simply put, some organisations will NEVER get much value from social software because the internal culture discourages collaboration, and encourages knowledge-hoarding, competition, backstabbing, secrecy and what-not. If Joe Manager at one of those firms puts in Yammer, or Jive, or Lotus Connections, or Fogcutter, or anything else, it's going to fail. In those cases, it has little or nothing to do with the technology.
(Disclaimer: I'm totally biased, as my company makes "enterprise social software". Take everything I say with a grain of salt as you see fit.)