Sysprep is a tool, that allows you to prepare a computer that is going to be imaged. This is useful if you have several computers of identical hardware, each needing the same OS + Applications installed.
Sysprep can also be used by PC Manufactures, to prepare the computers for shipping to an end user. Once run the end user will only have to enter, the computer name, admin password, Product key, instead of running setup from starch.
With the increase in virtualization cloning virtual machines, will speed up deploying new servers.
This is great when cloning VMware images.