This is perhaps the most useful free application i have ever come across over the web. Please consult the following video. Its basically a KM switching software and it works seamlessly across operating systems. Currently i have an escher like layout, going up to any of the edges of the monitor that i use here at work will swap the mouse and keyboard inputs to the other system. So effectively, with the use of the abilty to have my monitors with multiple sources i have the freedom to have four monitors, where three exist normally.
Quite a cool find i must say. Give it a try =)