Zynga (ZNGA) CFO David Wehner is leaving to take a "senior finance position" at Facebook (FB). He'll be replaced by chief accounting officer Mark Vranesh. Also, chief mobile officer David Ko has been named COO, replacing the recently-departed John Schappert; business development head Barry Cottle has been named chief revenue officer; and gaming exec Steven Chiang has been named president of games. The company is reaffirming its 2012 guidance. Zynga has already seen a tidal wave of executive departures. Shares +1.4% AH.