The motorcade that snaked through 1 Hacker Way earlier this year surprised even jaded Facebook employees, who are used to on-campus celebrity sightings and visits from politicians and world leaders. So a few days later, at the question-and-answer session that CEO Mark Zuckerberg hosts every Friday, an employee raised a hand to ask about it. It turns out the distinguished visitor — Treasury Secretary Jacob Lew — had not come to see Zuckerberg. Lew’s host? Facebook COO Sheryl Sandberg stood up and acknowledged that she had organized a breakfast with local business leaders for Lew that day. There were a few knowing chuckles, and Zuckerberg moved on to the next question.