There are other differences. Their e-zine is used to promote and support their hardcopy publication. Instead it provides an exposition of WBT best practices. The thinktank model is great for promoting its founder but it is not the best way to promote its participants. A virtual exposition is the most effective way to communicate WBT best practices and promote its participants.
Portals are very popular methods for promoting products and services.
They are part of the solution. But they are not a complete solution. Distribution is the main advantage that portals provide. You still have to actively market your products and services to your clients. I believe that a virtual web-based exposition is the best model to promote WBT products and services.