In some laptops, there is some hardware incorrectly detected as a mouse (Acer TimelineX, Lenovo/IBM thinkpad and maybe others). This causes that the indicator does not disable the touchpad.
If you are bitten by this bug, please download the attached script in /usr/share/touchpad-indicator and send us the output. The output can be very long, so better direct it to a file and attach it; you can do that executing this in a terminal: /usr/share/touchpad-indicator/device_list.py > my_device_list
Regards, Miguel Angel.
UPDATE: Since version 0.8.1 device_list.py is included with Touchpad-indicator.