[PatrickHenry]

A bit of Googling informs me that where we can observe eclipsing binaries, we can determine their mass (well, the smart guys can). Then, knowing their spectra, we presume to know how bright that kind of star is, so by observing their apparent brightness, and applying the inverse square law -- ta da! -- we know the distance. Very neat. But it seems that although binaries are common, it's not all that common to find them positioned just right so we see one eclipsing the other.

[Conan the Librarian]

Good answer! I still withhold some doubt of the validity of the scientist statement, but, I do feel better about it now.

Thanks!