It pays to write a tell-all tale from the belly of the beast. Greg Smith, the former Goldman Sachs executive who became an instant sensation when he ripped the Wall Street investment bank with a resignation letter published as an Op-Ed piece in the New York Times, has scored a $1.5 million advance to write a memoir of his experiences, The Post has learned. The Grand Central imprint of the Hachette Book Group secured the worldwide rights deal after a frenzied bidding war that riveted the publishing world this week. It had surpassed the seven figure mark by mid-week, and yesterday, the Penguin Group, the next-to-last ... (full story)