With new patches, multi-seat support for Wayland with the Weston compositor is beginning to work well. For showing off Wayland/Weston multi-seat handling, a video has been made.
Multiple seats can now be done with Weston whereby multiple keyboards and mice can all access a common workspace and from there work simultaneously.
The video description explains, "the weston compositor showing multiple seat support. A number of seats can be configured in udev, sharing a common work space. Each seat controls it's own pointer an has it's own focus, enabling collaborative user experience."