here are some pics of an official one I've just ordered from RS components.
note the silkscreen text on the 0.1" female connectors
they seems to be the same as the pictures available here
if that can help
the information about mega2560 are up to date on arduino.CC but not for the nano where it's the arduino.org website who have the updated data about it.
I don't know how they work to update their websites specs.