There's a blog post by Daniel Margolis on Chief Learning Officer about the risks of informal learning delivery. While the focus of CLS is generally on corporate training, many of their articles are relevant to learning in general.
The point behind this posting is that while informal learning has great stories to illustrate how learning can take place in social media settings, the lack of structure has risks. I think this is an important warning.
I see the excitement educators feel when they find a new tool. And while the instructional approach du jour may be fun to explore, I get concerned that the tools may be used without adequate study.
I have repeatedly commented about the lack of study on the most effective approach to the use of synchronous online education. I'm still looking for a research study on effective synchronous online instruction. If you know of one, or have conducted the research please let me know.
And, I'm always looking for examples of how to make online learning effective.