I heard Scott Ambler talking about the "Generalizing Specialist" on DNR 460.  He was stressing that this is the best type of person to have on your project team as they are more effective in practice, and I agree with him.

So what is a GS?  It is a person that is deep in one or more specialties (such as programming skills, DB skills, management skills, ...), but also has knowledge of other specialties, and is willing to learn more about the areas of which they are not specialists.

The challenges with specialists are several fold:

1. Do their jobs no matter what needs to be done.  For example a data modeler may just do data modeling, even if you don't need it.
2. They have problems interacting with other specialists.
3. Specialists hand off work to other specialists when they are done their work, leading to critical path and sequential project tasks (instead of in parallel)
4. The project is only as good as the weakest point in the chain of experts
   
5. A lot of extra work gets done all of which may not be needed

On the flip side of this is the generalist.  In this case, no one has the skills to get anything done.

The gist of this is that you want to:

1. Provide your expertise where needed
2. Learn where not a specialist in case you are needed at a later time
3. Provide different perspectives to other specialists to open their thought process
4. Be able to communicate so as to be able to complete work in parallel, and with higher quality.