223 Owen Thomas 01/17/08 02:39PM Filed to: nerdspotting nerdspotting SXSW 2008 Facebook Mark Zuckerberg sarah lacy SXSW Valleywag Facebook CEO Mark Zuckerberg will appear Sunday, March 9, at the SXSW Interactive Festival. He'll be interviewed on stage by BusinessWeek columnist Sarah Lacy. [Allfacebook]