#!/usr/bin/perl -slw

use strict;
use warnings;
use Class::Date qw(date);

my $date = new Class::Date;
print "from_date:  ",  date("2010-06-01");
print "mid_date1:  ",  date("2010-06-01") + '3M' + '1D ' - '1D';
print "mid_date2:  ",  date("2010-06-01") + '3M' + '1D';
print "to_date:    ", date("2010-06-01") + '7M';
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I “fanned” that approach, because, in my humble experience, when you start down the primrose-path of date calculations (in terms of what employees such as salesmen and accountants want to do with them ...), it just gets messier and messier.   But, because so darned many of us have been down that very same primrose-path so many times before, “all the work that went into” modules like this one are darned well worth it.   The client comes back to you with a new twist and you can still say, a la “A Chorus Line” ... “I can do that.”   Priceless.

use Delta_Days method to calculate number of days between 2 dates
then divide that figure with 2 or 3 whatever you want(since your post says 3 and the example you have given says 2).
then use Add_Delta_Days method to get the date from intial date to next date and so on....

Don't know about Date::Calc, but using DateTime...

use DateTimeX::Auto 0.003 qw/:auto/;

my $from = '2010-06-01';
my $to   = '2011-01-01';

my $diff  = $to->delta_days($from)->in_units('days');

my $mid_date_1 = $from->clone->add(days => $diff/3);
my $mid_date_2 = $to->clone->subtract(days => $diff/3);

print <<OUT;
from:   $from
mid 1:  $mid_date_1
mid 2:  $mid_date_2
to:     $to
OUT
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UPDATE: Just released 0.003 of DateTimeX::Auto because the script above was crashing on add and subtract.

use Time::Local;
use strict;
use warnings;

my ($from, $to, $range);

$from = '2010-06-01';
$to = '2011-01-01';

if (!($range = dateRange($from, $to, 3))) {
    print "Could not calculate.\n";
}
else {
    print "@$range";
}

sub dateRange {
    my ($fd, $td, $n) = @_;
    my (@range);

    $range[0] = $fd;
    $range[$n] = $td;

    $fd = [split /-/, $fd];
    $td = [split /-/, $td];

    ### Calculate timestamps from given dates
    ### Croaks on bad date, so have to eval just in case
    eval {
        ### Make sure to use timestamp from middle of day
        ### to eliminate potential problems with Daylight
        ### Savings or day rounding
        $fd = timelocal(undef, undef, 12,
            $fd->[2], $fd->[1]-1, $fd->[0]);
        $td = timelocal(undef, undef, 12,
            $td->[2], $td->[1]-1, $td->[0]);
    };
    return if $@;

    ### Calculate intermediate timestamps
    ### Reverse from timestamps back to dates
    for (1..($n-1)) {
        @_ = localtime($fd + ($td - $fd) / $n * $_);
        $range[$_] = sprintf('%04d-%02d-%02d',
            $_[5] + 1900, $_[4] + 1, $_[3]);
    }

    return \@range;
}
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