Xobni CEO Jeff Bonforte's job on the line?After the abrupt departure of Gabor Cselle, the talented VP of engineering at Xobni, a San Francisco email startup, talk is that CEO Jeff Bonforte might soon be out, too. At a startup, one of a CEO's main tasks is to attract and retain talent. In a comment on TechCrunch, Bonforte said Cselle wanted to run his own startup. Despite his rationalizations, there's no sugarcoating this fact: Bonforte just failed his most important test as a CEO."A quarter of the company's value walked out the door," a tipster says, and suggests that Cselle might take some of Xobni's engineering talent, including one of the founders, with him. Bonforte, formerly an executive at Yahoo, had a reputation there for being either loved or hated. At a large company, management can shuffle employees and executives around to make up for personality mismatches. At a startup, there's no room for such errors of judgment.