We've spotted a new feature, Dividers, in new Google Sites and a change in the way you add Google Drive folders.
On the Insert panel on the right there's a new section, Components, and in that you can now choose to add a Divider. This is simply a horizontal line to give a more visual way of splitting up your page.
To see some dividers on a page see our example new Google Site http://horizon.steegle.com/
Google has removed the Drive folder option from the Google Drive section of the Insert panel and you now add a folder by selecting the folder you want in the From Drive option instead.