After installing Ubuntu 14.04 on the Dell XPS 13 "Sputnik" the SynPS/2 Synaptics touchpad is not recognized and does not function properly. To fix this problem you'll need to blacklisting i2c-hid.
Use your favorite editor (gedit, mousepad, nano, etc) to add blacklist i2c-hid to your /etc/modprobe.d/blacklist.conf file.
In a terminal:
gksu mousepad /etc/modprobe.d/blacklist.conf
Then scroll to the bottom of the file and copy & paste:
save, exit and reboot.
Now everything works :)