Tim:

Per the perldoc:
http://perldoc.perl.org/CORE.html
... you can globally override CORE::GLOBAL::open with your own function.

It was a bit harder to do than I though though...

BEGIN {
  *CORE::GLOBAL::open = sub (*;$@) {
    ($package, $filename, $line) = caller();
    print "LOGGING: intercepted `open` call from ( package: '$package'
+, file: '$filename', line: '$line' ) with args: '??', ".join(", ",map
+{ "'$_'" } @_) . "\n";
    if(defined($_[0])) {
      use Symbol qw();
      my $handle = Symbol::qualify($_[0],(caller)[0]);
      no strict 'refs';
      if(@_ == 1) {
        return CORE::open($handle);
      }
      elsif(@_ == 2) {
        return CORE::open($handle, $_[1]);
      }
      else {
        return CORE::open($handle, $_[1], @_[2..$#_]);
      }
    }
    else {
      if(@_ == 1) {
        return CORE::open($_[0]);
      }
      elsif(@_ == 2) {
        return CORE::open($_[0], $_[1]);
      }
      else {
        return CORE::open($_[0], $_[1], @_[2..$#_]);
      }
    }
  };
}

open(my $fh, "<", ".bashrc") or die "unable to use hacked up open func
+tion: $!";
my $top = <$fh>;
print $top;
[download]

Which returns:

LOGGING: intercepted `open` call from ( package: 'main', file: './core
+over.pl', line: '34' ) with args: '??', '', '<', '.bashrc'
# ~/.bashrc: executed by bash(1) for non-login shells.
[download]

Note: i had done this before, but couldn't quite remember how to make it work with open($fh ..) instead of open(FH ..), so perl.com helped me out:
http://www.perl.com/pub/a/2002/06/11/threads.html?page=2