Beginning in PowerShell 3.0, there is a very easy way of determining the folder a script is located in: $PSScriptRoot. This variable always holds the folder path a given script is stored in.
This way, it is simple to load additional resources like other scripts. This code would load a second script called myFunctions.ps1 that is located in the same folder:
Just don't forget to dot-source the path (the dot before the path). Else, the path name will be outputted (and not executed).