I read about it in the specs with interest. Any hints about how to access it?
Select the camera, and look under the camera properties at the bottom - hover over the Composition button, and it will give you presets… I have no idea what they do as of yet.
They provide guides to help you compose your shots, according to things like the Rule of Thirds, Harmonious triangles and the like.
Yep all I had to do was select the camera, choose Object Data from the Properties Window header and there it was in the Display sub panel.