Here is yet another view at learning in groups. An article from Peter Henschel who is the Executive Director of the Institute for Research on Learning.
We most often learn with and through others.
Another sentence taken from the article:
"While recruitment and retention are the visible critical tasks, building continuous, pervasive, everywhere, all the time learning into work practices is the key new challenge for healthy enterprises. "
The article could be smaller, but its quite interesting. It places the learner in a company context, and, among other things, it describes how important being part of a group is for learning.