It is just the look and feel of how you can add paragraphs, images etc. to you page. This way of presentation is just very nice and feels robust and lightweighted.
I've seen this interface in the coming TYPO3 CMS and that is very neat. I believe they are using the Aloha editor for these things (http://www.aloha-editor.org/
Anyway, would be nice to have a simple and advanced option for edition pages like this...
Or maybe it is an idea to implement this for the front-end editing?