Amazing that nobody has mentioned the fact yet that a large number of Polish Americans are actually of Central-European Jewish background (I believe SInNYC might have indirectly alluded to that in his post upthread).
It would be a "Whitewashing" of Polish-American history to simply focus on Catholic Polish populations, with the obvious caveat as many other posters mentioned of historic patterns of inter-marriage between individuals from various country of origins over three major waves of Polish immigration to the United States.
Many Jews have ancestors who came from Poland but they do not identify as Polish or with the Polish American community.