Disclaimer: I work for Jive Software, one of the leading vendors (if not the leading vendor) of Social Business Software, so take it for what you will. I'm just a hosting engineer though - not a marketer.
That said, I think this question actually entails two separate issues. The first one is, will having their employees collaborate socially save them time, money, and energy? I've seen many, many examples of companies coming to depend on social software - there are plenty of examples on Jive's site (and it's not just blowing smoke, I've seen firsthand evidence of this and have even talked to some people on the sales floor who swear by it). Some customers I work with have grown so dependent on social software that they cannot tolerate even a minute of downtime. Social business is, in many ways, the wave of the future, and to criticize companies for trying to get on the bandwagon and realize the benefits for themselves is not something I'm prepared to do.
The other question is: Should the company provide a sandboxed environment for this kind of collaboration, or should they force their employees to use solutions that potentially violate their privacy or have other issues? I'm not going to say that any of the solutions out there such as Facebook have those issues necessarily, but they are obviously very much less sandboxed and do not have the interests of corporate and personal privacy in mind near as much as a vendor whose software can be sandboxed to provide some safety for personal information and company secrets.
At Jive we eat our own dogwood, and we use a social instance of our own software in the company, and I can't imagine working without it. But if a company were to force me to collaborate on publicly available sites where my grandmother (for example) would also post, I'd seriously wonder what they were smoking.