One of the nice features of Windows Phone 7 was the wide use of hinting throughout the system. In the case of the camera interface, this included a small preview of the last picture you took, a feature which always impressed other smartphone users.
Eagle-eyed reader Andrew noticed in a Microsoft video of the Nokia Lumia 920 this small strip has been replaced by simply an arrow. I think this does reduce a bit of the personality of the OS, but with Windows Phone 8 featuring multi-touch zoom in the camera interface this sacrifice may have been inevitable.
See the video at around the 1:30 mark onwards after the break.
Thanks Andrew for the tip.