No doubt the cover was intended as a satirical slap at all the people the New Yorker sees as the legions of bigoted and unsophisticated Americans who are supposedly falling for scurrilous rumors about Barack.
The cover is, actually, another example of what I was talking about last week: "The laughter [from the left] is derisive . . . a frequent default posture of the left, enjoying a contemptuous laugh at the expense of the hicks and the rubes who 'embarrass' sophisticates with their monolingualism, their proud pro-Americanism, their religiosity, their lapel flags and the like."
By the way, there's a picture of the cover over at The Corner.
Except this time, the joke's on The New Yorker.