Jeeeees, this has happened more often than i'd like to be honest, it's a bit unnerving for potential owners. They're still having problems with the development V10, they've installed a fire extinguishing system in them as a 'just in case' :s: It wouldn't stop me buying one if i had the money though!
I know someone who is on the list for one. (although more as a business venture... think he's gonna sell immediately). I would certainly have one though, especially after hearing the noise when it was on Top Gear.
theyre worth more money to buy secondhand and missing the waiting list at the moment which is always a good sign for the residuals so your mate should do well if he gets the right colour.
as for fire, werent audi going to install a fire trace system? a system of tubes that are pressurised with extinguiser and dont melt with heat only a naked flame throughout the engine bay? i think they use a similar setup on some cop cars, could be wrong tho