What does it mean to be "Hispanic"?

What does it mean to be “Hispanic” these days?

Apparently the Portugese Supreme Court Justice Bejamin Cardozo is not hispanic, but Sotomayor, who descends from Puerto Rico, an American Colony, is.

Are Brazilians hispanic? Doesn’t seem like it, despite Brazilians being Portuguese and Portugal being on the Iberian Peninsula — which in Roman times was “Hispania”.

Miguel Estrada somehow was an insult to hispanicdom and had his life ripped to shreds so they could keep the supposed “first latino” seat warm for Sotomayor. (And, in all seriousness here, what is the difference between “hispanic” and “latino”?)

Mel Martinez loves to paste on his thick latino accent when talking liberal talk about immigration issues, but somehow Rubio doesn’t make the cut as a true hispanic.

I am confused.