That's the problem with Mental Health and the diagnoses thereof- it's like trying to pin down a dot of mercury with your thumb- it keeps skittering away.
You can't positively say that a person has anything, you can only say that on a sliding scale, a person has "x" number of symptoms that either interfere with life, or do not. If they interfere enough, that person gets labeled with a diagnoses.
To make it more confusing, what is considered a mental illness today is not what was considered a mental illness 20 years ago, and will probably be different 20 years from now. So you can see that threre is no "universal yardstick" for mental issues.
Aspergers Syndrome, like ADD, like various Personality Disorders, are very nebulous diagnoses, but they do serve to describe certain behaviors that are on the smaller side of the behavioral bell curve. I know a few people whom I would say have Aspergers Syndrome to a greater or lesser degree. I don't know anyone, nor do I think it is even possible, for Asperger's Syndrome to be severe enough to actually interfere with a life in the way that, say, chronic schizophrenia does, instead those with Asperger's Syndrome sort of find their own level in life, and end up doing things that fit their lifestyle. So by Definition, it's not really a mental disorder.
I can generally tell someone who has Asperger's Syndrome within a minute or so of conversation.
There are quite a few of us who believe that pretty much all of these diagnoses are a waste of time, but to them I say, what is better- looking at someone and saying "there's just something about that guy that Ain't Quite Right", or actually finding out what the common symptoms are so that the sufferer sort of know what to expect?
As someone who was diagnosed with adult ADD, after a solid week's worth of testing at Mass General Hospital in order to test some new ADD drug, I get a little annoyed at people who write off these diagnoses, but at the same time I certainly see and agree with their point that you can't label everything as an excuse or just to categorize someone. We just have to find a balance between ignoring it and making mental health a catch-all excuse.
Overall, I'd prefer to hang out with someone with Aspergers than, say, someone on the manic phase of bipolar disorder.
edit: I scored a 12 on that test.
-James