My opinion is that E2.0 is a set of new fancy tools, similar to what people have beem using outside company. These tools can sure be powerful, but the problem is that you need devoted users,customers or partners that contribute content before these tools become valuable. How to get these devoted users, I think, the greatest challenge of all for companies looking to harness these tools for business. Our company (tech company of 21 000 people) has been using Yammer for about a year now. After the first hype of couple months, the usage of the tool dropped and we (or at least I am) are back in sending emails back and forth again :)