Check out this new book about our lot:http://www.economist.com/node/21542170
OK, so who knows (or is) a hyperpolyglot?
I know several people who can speak three languages at a native or near-native level. But all of them had lots of exposure to the languages as children.
I know several more people who can read twice that many languages with relative ease. Decipherment, esp. of related languages, seems the easiest skill to acquire--or maybe I just think that because it's easy for me.
I have one friend who is able to use about fifteen languages, nearly all of them learned in adulthood. But his level of proficiency varies from jaw-droppingly good to merely functional.
In any case, I've never seen anyone with the crazy numbers they talk about here.
There may be so many variables involved--number of languages, level of proficiency, type of proficiency, dead vs living languages, etc.--that comparisons between people are meaningless. But it's still fun to think about--or try and touch--the extreme end of linguaphile lunacy.