The welcome screen for Windows 8 has been leaked (and confirmed as real). The below screen show is the current Windows 8 Welcome Screen and is visibly based on the Windows Phone 7 lock screen - which is impressive in itself.
You can only change the background image of the Welcome Screen at the moment, but the display includes the time, day of the week, the date (month and day) and icons for power management (for portable machines only) and ease of access. More things could be added in the future. Aside from the functionality that has been shown in the leaked builds, there is also evidence of more features to come.
Tablet-type devices will be capable of logging on through a drawn pattern - like Android-based devices and Microsoft will also be supporting extensible Welcome Screen-based audio controls, which gives users the ability to control music playback when the machine is locked.