This is a must-read post by Mike - here is a snip below:

The most interesting and potentially most profitable use of Web 2.0 techniques in the Enterprise is however in the customer facing areas of organizations and in a few specialist internal business areas. The specialist areas are things like product development where customer involvement and discussion in product design and development via blogs, wikis and discussion forums is a very fertile area for innovation and development. The other internal area which could benefit from these techniques is training where the use of video, VOIP, messaging, chat and even mobile delivery has considerable and extensive potential.