yeah, i haven't heard of the hyper ps 6.0 coming in a 90" head. they did sell the 95" head box beam on TW a while back, and in europe.
as far as federer, he probably uses a custom ps 6.0 original with a custom 90" head. there was another thread w/ a link to an article about the wilson "pro room" where they basically did all types of customizations for particular players. this would include drilling a different string pattern in a racquet than what was commercially available.