How to sysprep Ubuntu to take its image

I am using fog to install images in my office. To clone and deploy Windows images, sysprep is used to generalize the Windows and to make sure it loses all the unique information like names etc.

Now I have to take image of Ubuntu on fog server and deploy it on 20 PCs. I am just wondering how to "sysprep" Ubuntu for this process.

Check this Ubuntu Forums thread. User Cheesemill provides the following advice in response to the question what is the Ubuntu equivalent to sysprep for Windows?

You can boot the Ubuntu installer in OEM mode to achieve the result you are after.

When you boot the installation media, hit SHIFT to get to the installation menu, then hit F4 and select 'OEM Install'. When Ubuntu has finished booting install the system as usual, you will be prompted for a temporary username and password.

When installation has finished, boot the system and log on with the temporary username and password you created earlier, you can now make any other alterations to the system that you want, for example installing extra software. When you're all done just double-click on the 'Prepare for shipping to end user' icon on the desktop and then shut down the machine, it's now time to take your image of the drive.

Next time the machine is booted the user will be asked to set up their account.

You may also find something useful in this man page

Have you had a look in the Ubuntu automated deployment guide?