FileSystem Module - Get File Encoding and Test Files
Download: File System module - Get-DTWFileEncoding

This module contains file system utilities, currently only a function to detect the encoding of a file. This function, Get-DTWFileEncoding, looks for a Byte Order Marker; if not found, analyzes the content of the file to attempt to determine the encoding type. Comes with sample files with various encodings and a test script.

For more information see: http://danspowershellstuff.blogspot.com/2012/02/get-file-encoding-even-if-no-byte-order.html