I think that both generalists and specialists are useful. I have found that event the most diverse generalist is a specialist in at least 1 category. I am this person, my specialty is in database (design/development) and OO client server coding. I can and have programmed in a plethora of languages also. When my company finds out I can do the other stuff they use me to do these tasks also in addition to DB stuff. I always refer my coding to review to a specialist until I have a handle on the api, and I often differ to the specialist on how to do something in the platform that they are good in.

I have also found that some specialists are not worth their credentials in all of this. Some people are just better developers than other no matter how specialized their training and experience are.

Finally, I prefer people with diverse experience to have on my team as long as they have some specialities. The generalists bring a broader view of the whole picture to the table and the specialists bring a more microscopic view in many cases.

CASE Example:

Working with a whole bunch of JAVA developers on a project and part of the process was scrubbing data. Since they were all specialists in JAVA they solved the problem in JAVA. When I came along to do some JAVA with them I asked why are you doing this scrubbing in JAVA? I took them an insane amount of time to process this scrub. In a standard SQL proceedure I could scrub the data in about 1/10 the time. They wanted to avoid babel code as much as possible, and I totally understand why they wanted to do that. This type of JAVA only thinking is what eventually sunk the project after 1 year.