I've often heard admins discuss this over lunch breaks. But securing partitions on servers isn't enough. Encrypting partitions on laptops and desktop of users throughout the network, sounds preposterous. But take a deep breath and consider the repercussions of your CFO loosing his laptop. Gah! I'm sorry to scare you.
LinuxPlanet has a tutorial which partitions the disk using the cryptsetup-luks utility. It's easy to setup and use and requires virtually no configuration. There's a more detailed tutorial on using the cryptsetup-luks tool on its website, as well as on on feraga.
You can also use Cryptsetup-luks in innovative ways. For example, you can use it to encrypt a particular partition and then in a move straight-out of a Hollywood flick, use a USB stick as the key.