Mexicans vs. the enemy within

Jane Galt succinctly refutes the idea that the current massive influx of non-English-speaking, non-assimilating immigrants is a unique threat to our nation. She describes the eventual assimilation of even the most 'foreign' immigrant populations, leaving only their tastiest cultural contributions behind (hello, bagels and falafel!). She also offers a striking counterexample, an immigrant group who successfully maintain separate, non-English-speaking communities and resist Americanization by removing their children from public school after 8th grade, yet are seen as either inspirational or charmingly quirky by most Americans. (Read her post to find out the identity of this group, if it's not clear.)

On my better days, I like to believe the panic about the Mexican menace (the anxiety over hearing only spanish in some parts of town, the resurgent fears of 'Popism,' the conviction that they're really after American welfare checks) isn't really racist, is just the result of lack of familiarity. On my less charitable days, I echo JG's question: "Can someone explain this in terms that don't devolve into 'But the Mexicans are brown?'"

(Incidentally, on the welfare/immigration issue, I meant to link earlier to this recent Cafe Hayek post. Excellent title: They're So Lazy We Must Use Force to Stop Them from Working.)

UPDATE: Apparently due to some negative comments, Jane Galt feels compelled to explain herself further on this issue. I think the original post was nicely concise, but here she fleshes out the history of immigration and assimilation in the U.S.