Disable Touchpad While Typing does not work

This command worked for me (1 is the number of seconds to wait after the last key is pressed before re-enabling the touchpad, change it to whatever value you desire):

syndaemon -i 1 -K -d

Just add it to Startup Applications to make it work after reboot/shutdown. To see more options type this command in a terminal:

syndaemon --help or man syndaemon

Like others here the syndaemon utility solved my issue. For me the syndaemon was already running.

After playing with it and reading some of the other answers here I determined that the cause is the -t option.

The option must have a bug because when it's specified I can still scroll and tap while typing. However, if you omit the option entirely then everything works fine; the entire touchpad is disabled as expected while typing when you don't include the -t option. I simply run the following to restart syndaemon without -t.

$ killall syndaemon
$ syndaemon -i 1 -KRd

• -i allows you to specify how long syndaemon should wait after typing has stopped before re-enabling the touchpad. One second is what was already running and seems to be fine for me.
• -K tells syndaemon to ignore modifier keys and modifier+key combos when monitoring keyboard input.
• -R tells syndaemon to use the "XRecord" extension instead of polling for keyboard input. I imagine it uses this for performance reasons; the extension probably reports when typing activity stops instead of depending on syndaemon to continually poll the keyboard to see if there is input.
• -d just tells syndaemon to run in the background when you start it, without blocking your terminal input. If you don't include this option then syndaemon will stop when you close your terminal.

So in the end it's the -t option that is the culprit here. Just get syndaemon running without it and all is well.

PS - My machine is an original Lenovo Yoga 13 in case anyone was wondering. I completely blew away my Windows install and replaced with Ubuntu 14.04.