I think an interesting way to look at this is what proportion of questions answered are tagged with the top tag(s). It gets a little hard to get actual percentages from the user pages since questions can have multiple tags, but let's look at just the top tag. For example (snapshot as of 8/1):
Jon Skeet: 4728 answers, 2336 tagged C# = 49%
Marc Gravell: 3635 answers, 2427 tagged C# = 67%
Tim VanFosson: 2726 answers, 456 tagged C# = 17%
S. Lott: 1863 answers, 927 tagged Python = 50%
JaredPar: 2062 answers, 870 tagged C# = 42%
Greg Hewgill: 1373 answers, 177 tagged C++ = 13%
Joel Coehoorn: 2274 answers, 641 tagged C# = 28%
It's certainly not definitive, but I think you can safely say that, with the exception of me, the top 5 tend to be more specialist (at least in their answers), answering more questions in their top-tagged area. Personally, I feel that I tend to be more of a generalist and I think the numbers bear that out. Even if you combine asp.net and asp.net-mvc to make it my top "tag", my percentage of questions answered in that "tag" only rises to 27%. If you extend that to the top 7, Greg Hewgill would also appear to be more of a generalist, while Joel Coehoorn seems to be somewhere between.
Probably more important are the sheer number of questions answered. With a couple of exceptions the scores reflect basically the number of questions answered with everyone (except S.Lott: 2.7; Greg Hewgill: 3.3) averaging ~2 upvotes per question. It's really the number and quality of answers that you contribute, not specialist/generalist that has the biggest impact on your score.