This task has two parts: one is to find the first and last day of the current week, the other is to print the interval as a human-readable format. For the first, we'll use the Date::Manip::Date_GetPrev function which does the right thing. I have to hand-roll the second one.

Here's my solution. This assumes your dates start with Monday.

#!perl                                                                
+  
use warnings; use strict;                                             
+  
use Date::Manip;
my $mon = Date_GetPrev("now", "monday", 1, 8);       
my $fri = DateCalc($mon, "+4days");      
my($mony, $monm) = UnixDate($mon, "%y", "%m");
my($friy, $frim) = UnixDate($fri, "%y", "%m");
my $r;                          
if ($monm == $frim) {           
        $r = UnixDate($mon, "%B %e-") . UnixDate($fri, "%e, %Y\n")
} elsif ($mony == $friy) {                           
        $r = UnixDate($mon, "%B %e-") . UnixDate($fri, "%B %e, %Y\n")
} else {
        $r = die "homework for the reader";
}
print $r;
__END__
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The builtin function localtime gives you all the elements you need.

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
    localtime(time);
my $monday = $mday - $wday + 1;
my $friday = $mday - $wday + 5;
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Of course this doesn't work if you aren't in the middle of a month (e.g. if ($mday - $wday + 1) < 0). You could take your time() and add or subtract 24*60*60 seconds per day to get the right unix time, then convert to date with localtime()

my @Now = localtime(time);
print "Today: $Now[3] - $Now[6]\n";
my $Mon = time - (86400 * ($Now[6] - 1));
my @Monday = localtime($Mon);
print "Monday: $Monday[3] - $Monday[6]\n";
my $Fri = $Mon + (86400 * 4);
my @Friday = localtime($Fri);
print "Friday: $Friday[3] - $Friday[6]\n";
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This won't work in the following cases:

#!/usr/bin/perl
use strict;
use warnings;
sub     this_monday_thru_friday {
    my ($now,$wday,$mon_secs,$fri_secs,@mth,@mon,@fri);
    $now = time();
    $wday = (localtime($now))[6];
    $mon_secs = ( 1 - $wday ) * 60 * 60 * 24 + $now;
    $fri_secs = ( 5 - $wday ) * 60 * 60 * 24 + $now;
    @mth = qw( January February March April May June
               July August September October November
               December );
    @mon = (localtime($mon_secs))[3..5]; # mday,month,year
    @fri = (localtime($fri_secs))[3..5]; # mday,month,year
    $mon[2] += 1900; # change monday year to four digits
    $fri[2] += 1900; # ... do the same for this friday
    return $mth[$mon[1]],@mon[0,2],$mth[$fri[1]],@fri[0,2];
}
# Example output: August 24 2009 August 28 2009
printf "%s\n", join " ", this_monday_thru_friday();
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