It's just the wishful thinking of a graphic artist.
The New Yorker just published a magazine cover that depicted Bert and Ernie watching the Supreme Court (who had just declared DOMA to be unconstitutional) on TV while Ernie lays his head, affectionately on Bert's shoulder. These two guys live together, so they must be gay, right?
Of course, this has garnered all kinds of reactions, but it's most important to point out that Sesame Street denies this interpretation, saying that Bert and Ernie have no sexual orientation, whatsoever. Some LGBT enthusiasts have long desired to see these two as a gay couple, but it's nothing more than slash fiction. On the cover of the New Yorker.
Bert and Ernie teach kids about friendship - can't that be enough? Can't we even watch a puppet show without politicizing it?