No one seems to ask this simple question, so I will.
My PowerShell script file is located: C:/this-folder/that-folder/another-folder/powershell-file.ps1
C:/this-folder/that-folder/another-folder/powershell-file.ps1
In PowerShell 3.0 you can get it with the new $PSScriptRoot variable, and with $PSCommandPath you can get the full script path.
$PSScriptRoot
$PSCommandPath
There's also a great post by MVP Keith hill you may want to check:
http://rkeithhill.wordpress.com/2010/09/19/determining-scriptdir-safely/