The Wall Street Journal details the connection of the false passport trade to the MH370 incident, while Phuket-wan has the story of exactly how the Italian man (the other is Austrian) had his taken during a moped rental in Phuket.
Unfortunately in many parts of the world, rental agencies require holding a form of identification while the rented is off enjoying the vehicle, and what do tourists typically have on themselves? A passport. Although we've never personally allowed anyone other than consulates to hold onto our passports, we have given our driver's license to secure contracts. Thankfully we've always received it back, but the Italian's first-hand story has us on higher alert, as it should for all travelers.
Never ever part with your passport unless it is for a legitimate and verified reason (such as sending away for an entry visa, or for a minute or two while a hotel receptionist enters the details into a reservation), lest it never return because of a seemingly innocent mistake. Mistakes with passports are hardly innocent, and this sort of crime is hardly restricted to Southeast Asia.
It's 10 o'clock. Do you know where your passport is?