As Sweet explains, Rahm is a sensible back channel (though seemingly a rather public one). His father is an Israeli immigrant. He's very tuned into Israeli politics.
More interesting to me is Barak. He's a former Labor Prime Minister now serving as a very powerful Defense Minister in Netanyahu's coalition government. (He bolted from Labor a while back and now is basically in his own mini-party.) But the talk in Israeli politics of late has been that Obama v Romney has actually become a division point between these two men -- with Barak basically siding with Obama, both in terms of the presidential elections but also, more importantly, on the question of policy toward Iran. (Obviously, the two can run together. If you think Obama is going to win, that speaks strongly to policy question.) Meanwhile Netanyahu is hostile to Obama, mainly on Iran but by a proxy of sorts in the context of the presidential election.
So it's sort of curious to me seeing Barak conveying this message, if that's what is happening.
Curious to hear what other Israeli politics watchers make of it.