This works for me.

D:\>file Simple.xml
Simple.xml:     Text file, UTF-8 format

D:\>cat Simple.xml
<?xml version="1.0" encoding="UTF-8"?>
<root>
    <foo>
        bar
    </foo>
</root>

D:\>od -h Simple.xml | head -1 | cut -c 1-24
0000000000    EF  BB  BF

D:\>cat Simple.pl
#!perl

use strict;
use warnings;

use XML::Simple;

local $XML::Simple::PREFERRED_PARSER = 'XML::Parser';

my $file = shift @ARGV;
my $xml  = XMLin($file, ForceArray => ['map'], KeyAttr => {});

D:\>perl Simple.pl Simple.xml

D:\>perl -v | head -8 | fmt -w 68

This is perl 5, version 12, subversion 2 (v5.12.2) built for
MSWin32-x86-multi-thread (with 8 registered patches, see perl -V for
more detail)

Copyright 1987-2010, Larry Wall

Binary build 1202 [293621] provided by ActiveState
http://www.ActiveState.com Built Sep  6 2010 23:36:03

D:\>
[download]

Simple.xml is a simple XML document in the UTF-8 character encoding scheme of the Unicode coded character set. It has a UTF-8 byte order mark in it. XML::Simple handles the XML document properly.