"Sophia" over at Solomonia has reached the same conclusion as me about pro-Israel voices being called "traitors". While I based my observation on the posters on the Huffington Post, who are admittedly outside the mainstream (we hope), she talks about her personal experiences and "MSM bloggers".
As the Obama administration continues to give off the impression that to be pro-American is to be anti-Israel (an admittedly overly simplistic statement), I wouldn't be surprised if we see more of this kind of rhetoric from Israel's critics. It's ironic, of course, as the only people the Arabs don't like more than the Israelis are Americans, but we've seen that in the leftist mind at least that doesn't matter. If the USA is as antagonistic towards Israel as Syria, the Arabs aren't going to start liking us again. They're just going to be fellow travelers until Israel is destroyed, and then move on. It's important that we battle the accusation of "traitor" wherever it arises, online or in government, as it is a very slippery slope from then on. From the perspective of the Holocaust (and Jewish history in general), it's very disturbing language.