ManyMouse is supposed to use evdev for mice, but unfortunately I have found that on my laptop, and the Asus EEE Pc, it detects exactly one mouse, but wont read any positioning information about it.
Doing a sudo chmod 777 /dev/input/* works (and allows multiple mice to be detected) - but it seems only on desktop machines
Doing a sudo chmod 777 /dev/input/* works (and allows multiple mice to be detected) - but it seems only on desktop machines