This post explains how to use modules, a new feature in Windows PowerShell CTP2. You must be using at least Windows PowerShell CTP2 or later to use this technology.
From the previous post, you might assume that modules can only be DLLs. This is not the case. In fact, modules can either be a single script, a collection of scripts, or a DLL containing cmdlets or providers. Modules allow you a cleaner way to work with groups of scripts, because they can contain private variables that only those scripts share. You can also refer to a function within a module, which allows you to group commands more logically and to use more common function names without fear of overwriting the names of other functions.