Like Andy said, I don't think it's a mental disorder unless taken to the extreme to the point where it seriously interferes with your own or others' lives. Most people have a few things they are rather perfectionistic about but I'd consider that to be more of a quirk, not a disorder.
My impression of perfectionism (I haven't read a lot at all) is that when something possesses a flaw, it's viewed as completely valueless. That can be a big problem if you're evaluating yourself, others, even ideas, but mostly yourself and others.
From what I remember about object-relations theory, a big milestone for a person is being able to integrate good and bad aspects of something into one thing. If you don't, you're in trouble because everything has bad aspects and you have to develop tolerance if you want to maintain a relationship with those things, instead of just rejecting them and searching for illusory perfection.