“the crew working on the next Harry Potter movie has 2 Canon EOS 5D Mark II cameras on set for filming. And, theyÃ¢â‚¬â„¢re using Panavision lenses on the 5D2s.”
Read more here: http://blog.planet5d.com/…
That's Iron Man 2 and Harry Potter apparently using the 5D Mark II's. It's safe to assume updated firmware is being used.