My touchpad was super sensitive. Every time I typed something and my palms ever so slightly accidentally touch the touchpad the cursor would went places and sometimes clicking something and that is bad.
First I thought this was strictly a hardware problem, so my first and temporary solution was to avoid touching the touchpad  while typing, and it was not easy.
After a while and some googling I learned that this is a common problem in Ubuntu and this is how to fix super sensitive touchpad in Jaunty Jackalope:

• make a text file without extension called options in /etc/modprobe.d/ .
  You have to be superuser to make change in system file, in this case make a new file called options. So open your terminal and type this:
  

  sudo gedit /etc/modprobe.d/options

• add this line in it:
  options psmouse proto=imps
• save and restart
  

It works, now the touchpad is less sensitive. But the side scroll function is gone. Not a perfect solution, for now I prefer this to jerky touchpad until better solution arrives.

update Aug 30, 09:

I found the perfect solution, meaning there is no function sacrificed. Not just one solution, there are two of them. Obviously you must choose only one.
First method is a non-GUI, follow the instruction at Ubuntu help.

Second method is easier and GUI-er. Just install Touchfreeze, you can find it in Synaptic Package Manager. It's an application that disables your touchpad while typing and re-enables it after configurable time. Add it on your autostart list to make life easier.

source : eee user forum

keyword : jerky, sensitive, touchpad, fix, jaunty