Millions of reasons why Google's glad to have Ben Ling backDon't feel too sorry for Ben Ling, the star product marketer who leapt from Google to Facebook back to Google in less than a year. Facebook COO Sheryl Sandberg — herself a Google alum — has threatened not to let Ling keep the shares he earned to date. It was a petty move that goes against Valley standards of on how to treat departing employees, not to mention Facebook's own practice in such matters. But it's not like the loss will sting Ling. Google SVP Jonathan Rosenberg, who's said to be a big fan of Ling and recruited him heavily to come back to the search engine, is taking care of Ling with a "multimillion-dollar signing bonus," according to one tipster.