A. Several people have asked me this recently. They assumed that Windows 7 slates are running some minimal version of Windows 7 or something based on the Windows Phone 7 platform.
The reality is that Windows 7 slates run the full version of Windows 7. It could be the Home, Professional, Enterprise, or Ultimate SKUs depending on the manufacturer of the slate device and the features desired. There's no special version of Windows for slate devices. A slate is just another form factor for the Windows OS, just like desktops, notebooks, netbooks, and tablets.
For consumer-targeted Windows 7, slates you're likely to see a version of Home or Ultimate. Enterprise-targeted slates are likely to run Windows 7 Professional (and organizations could upgrade to Enterprise).