(2) Became popular in the american language through its occurence in a phrase of the old nazi-time german anthem, re-used by punk bands ("california über alles")
(3) Is now used as a substitute for "really" or "very" etc.
(2) "...Deutschland über Alles..." (Germany above All Things)
(3) This website is über-informative
2. More modernly this word has become mainstream in American pop culture as an adjective to add emphasis to the impressiveness of something.
i.e.: Heide Klum is an über-babe.