TinyMCE Block Concept
This is a demo of the a possible block concept around the TinyMCE editor, it uses the InLite theme of TinyMCE together with some hacky magic around adding blocks and turning them into editable areas.
Note: You need to select something, or be on a new line to get the controls from TinyMCE to show up.
You can imagine this inside Wordpress, where you would have some different options when implementing it, you can just do it "stock" just like Wordpress has now and this page when initially loaded, with a title and a rich text area, you can then perhaps enable the "block" system on some pages, or provide fixed templates that contain certain block elements predefined (probably good for very complex page structures).
Extra controls for moving the blocks around, settings, would be needed.
You can also imagine completly custom blocks, where you perhaps do not have any layout but a Wizard or some other dialog/mechanism of creating a specific sort of content, say a chart for example.
It is important to make a distinction between a Page Layout Engine (when constructing a website) and a Content Layout Engine, that this would facilitate, you would have to provide controls in order to be able to lock down the type of blocks and flexibility that the customer can have.
Please note that all this is just a concept test, don't recommend using any code etc from this. If your interested in the InLite theme, check out the tinymce.com website and docs.