We use Chatter where I work, and I think it's used pretty successfully. It's not exactly a "social network" because, let's face it, when you're at work, you're

We use Chatter where I work, and I think it's used pretty successfully. It's not exactly a "social network" because, let's face it, when you're at work, you're (hopefully) going to be a lot more professional and not treat it like Facebook. Instead, I'm seeing our sales team communicating with the product team to ask questions about our products, post suggestions they've received from clients, ask for example clients, etc. It seems to work. It just doesn't work like Facebook because, well, it's a completely different environment.