While multiple mouse pointers do not make sense on a single computer there is a significant benefit in collaboration scenarios.
Microsoft conducted a research for students and developed a solution for multiple mouse cursors on one PC:
Microsoft's MultiPoint technology can be used in a computer lab and applied in a classroom with students participating while a teacher controls the application. Several educational software already use the Microsoft MultiPoint platform today.
The disadvantage of Microsoft's MultiPoint solution, however, is that all users need to be sitting directly next to the shared computer. Alternatively, you need expensive custom hardware and mouse devices with extra-long USB cables and expensive industrial USB hubs with 20+ sockets to allow students in a classroom to connect to the central PC.
MultiMouse instead allows meeting participants to use the mouse and keyboard of their own computer while be able to collaborate on the same desktop screen. The remote cursors are sent via a standard WLAN or Ethernet network.