Powershell-FTDetect is a project mainly written in Vim Script, it's free.
ftdetect plugin for Powershell files
This is a mirror of http://www.vim.org/scripts/script.php?script_id=3658
Provides initial ftdetect support for Powershell files. Best used with the Windows Powershell Syntax File, Windows PowerShell Indent file and Filetype Plugin file (vimscript#1327, vimscript #1815 and vimscript #1816).