Some are getting overly excited about Google Web Designer and saying goodbye to Flash, "Its the final nail on flash's coffin." That's still a bit optimistic though seeing as this web design tool isn't yet even supported under Linux and there's still plenty of existing Flash content on the web, including videos not yet supported via HTML5 video.
Google Web Designer supports even creating HTML5 ads, offers various illustration views, can be viewed in both a design mode and the code itself, supports full 3D authoring, and provides two animation modes. Right now Web Designer is just available for Windows and OS X, though Linux support is likely given Google's history. Seeing as most of the HTML "What You See Is What You Get" editors on Linux are crap, it will be rather nice to see this software on Linux for publishers.
Google Web Designer can be found here. Below is a demo.