In the political minefield that is the Israeli-Palestinian conflict, the issue of Jerusalem hangs like a hornet's nest on a limb over a pile of unexploded ordnance. That's why many people caught their breath recently when Sen. Barack Obama, fresh from securing the Democratic nomination, walked through that field and stood face to face with the humming problem. Obama grabbed the Jerusalem hornet's nest and shook it hard. Or at least it seemed that way for about 24 hours. Speaking before the annual gathering of AIPAC, the pro-Israel lobby, Obama reassured Israel supporters that he was ''speaking from my heart,...