Some have asked for the new G+ cover dimensions. G+ automatically scales the cover depending on the size of the browser window, up to a max of 3 columns of content and a total width of 1600 px. At that width, the left panel is 520px wide (just slightly under ⅓ of the overall width), which leaves a cover image size of 1080 wide and 608 px high. Of course, you can upload larger images up to 2120px x 1192px, if you like. If you do your math’s you’ll realise that it is exactly 16:9 widescreen HD format, at 1080 wide just a bit scaled down from 720p (1280 × 720).
There you go.
Disclaimer: The numbers provided are not official number, but based on our mac screens in my studio at this very moment. Milage on other screens or systems may vary, and future changes may or may not apply. Now I sound like a lawyer 😉