#!/usr/bin/perl --
use strict;
use warnings;
use Time::Piece;

Main( @ARGV );
exit( 0 );

sub Main {
    my( $now ) = @_;
##    $now ||= Time::Piece::localtime->strftime('%m-%d-%Y');
    $now  ||= "08-13-2013";
    my $raw =
'Date        Time      Tag
08-13-2013 21:22:17  Yes
08-13-2013 22:22:17  No
08-14-2013 11:22:17  Yes
08-13-2012 21:22:17  Yes
08-13-2011 22:22:17  No
08-14-2012 01:22:17  Yes
';;;;
    my( $header, $todaytes ) = rubberBiscuit( $now , \$raw );
    print $header;
    print "$_\n" for @$todaytes ;
}
sub rubberBiscuit {
    my( $now, $file ) = @_;
    use autodie;
    open my($in), '<', $file ; ## or die by autodie
    my @today;
    my $header = readline $in;
    while( readline $in ){
        my($date, $time, $tag ) = split ' ';
        if( $date eq $now ){
            push @today,
            join ' ',
                Time::Piece->strptime(
                    "$date $time", '%m-%d-%Y %H:%M:%S',
                )->strftime('%Y-%m-%d %H:%M:%S'),
                $tag,
            ;;;;;
        }
    }
    @today = sort @today;
    return $header, \@today;
}

__END__
Date        Time      Tag
2013-08-13 21:22:17 Yes
2013-08-13 22:22:17 No
[download]

I think this can be simplified somewhat. The following just demonstrates the basic selection/sort logic without regard to how you want to handle the file itself.

#!/usr/bin/perl

use strict;

use POSIX qw(strftime);

my @orig_data = (
'Date        Time      Tag',
'08-13-2013 19:22:16  Yes',
'08-13-2013 18:22:17  No',
'08-13-2013 21:22:17  Yes',
'08-13-2013 20:22:16  Yes',
'08-13-2013 23:22:18  Yes',
'08-13-2013 22:22:17  No',
'08-14-2013 01:22:17  Yes',
'08-14-2013 00:22:18  Yes',
'08-14-2013 03:22:19  No',
'08-14-2013 02:22:18  Yes',
'08-14-2013 05:22:28  No',
'08-14-2013 04:22:29  Yes',
'08-14-2013 07:22:19  Yes',
'08-14-2013 06:22:18  Yes',
'08-14-2013 09:22:19  No',
'08-14-2013 08:22:19  Yes',
'08-14-2013 11:22:19  Yes',
'08-14-2013 10:22:20  No',
'08-14-2013 13:22:20  Yes',
'08-14-2013 12:22:20  No',
'08-14-2013 15:22:21  Yes',
'08-14-2013 14:22:20  Yes',
'08-14-2013 17:22:21  Yes',
'08-14-2013 16:22:22  No',
);

# this should be used instead of the hard-coded value below:
# my $today = strftime("%m-%d-%Y",localtime());
my $today = '08-14-2013';

my @todays;
for ( @orig_data ) {
    my ($date,$other) = split(/\s/,$_,2);
    next unless $date eq $today;

    push(@todays, "$other");
}

# NOTE! this will reverse the order of Yes and No if they have the sam
+e time.
@todays = sort(@todays);

for ( @todays ) {
    print "$today $_\n";
}

__END__
[download]