since no one replied , i'll add to my cheap excuse of an answer
non-english music made a lot of headways in the USA in the last 20 years.
Starting early with Nena - 99 Luft Balloons and Falco -Rock me Amadeus (the translation of both songs originated from their popularity in the english world) and moving to later "success" like La Bamba - Macarena - Los Ketchup and other latinos hits.
Even in metal , Rammstein is loved but they sing german ( for what i know , only 2 songs have english version).
On the flip side , still wondering why the russian Serebro never burned the chart this side of the atlantic ... i mean Mama Luba
got a catchy beat and the video is mostly SFW porno
With that said , i think Psy is getting noticed because he is a LFMAO knock-off.