In a blog post Paul Thurrott has posted two interesting images of the upcoming Windows 8.1. The first is a an image of the start button which is making a return. He notes that in the Milestone Preview build of Windows 8.1 there is no way to turn off the Start button, however this could change.
The second image shows the ability to add a desktop wallpaper to the Start background. This is turned off by default.
He also confirms that a boot to desktop option is available, and this is also disabled by default.
Source: Paul Thurrott