It's easy to find magazine and journal articles touting the need to use these tools, but finding hard data ... well that's another matter. My research has led me to some neat places and sources. Here are just a couple of items you may find useful. I suspect I will have to conduct my own research, with truly measurable metrics.
By providing a common infrastructure for these exchanges, this content becomes searchable and can be included in reports and analytics that provide more insight into the meta-discourse around formal content. Many organisations continue to measure learning through statistics such as the number of courses completed or against a tick box of key staff competencies.