Indeed, Thermald is the software you need and detailed instructions are available at the official Ubuntu site.
It's as easy as
sudo apt-get install thermald
on most machines.
How I use thermald is in sem-automatic mode: I have 2 /etc/thermald/thermald.conf files and when I need to extend my battery -life, I copy thermald.conf.quiet over the existing file or when performance is needed thermald.conf.performance gets copied over...
This is just one little part of a script that uses pm-powersave, gsettings, ... to regulate my performance settings. (Also, my on-board NVidia is always disabled unless I need it to do heavy-duty gaming or drive my HDMI port.)
If you're freaked out about your T°, you want even more finely tuned control and then you need the lm-sensor
package which I did fine-tune on 12.04 but whose fine-tuning I lost when my upgrade from 12.04->14.04 crashed my system. (I have it installed but not fine-tuned yet) so if you want to go down this road, drop me a note.