Working from bottom to top, some suggestions for making this post more useful:

• Tell us a bit more about the meaning (as used here) of "approximate." Is 15 days approximately "a week" ... or "a month?" Does 183 days approximate "a year?" What number of seconds become (roughly) "a minute?"
• Re "Any interest:" A clear and somewhat more expansive announcement would probably generate more interest.
• Re the address: better provided as a link -- see Markup in the Monastery and note also that while a site cited largely answers the questions, content here is durable; the Wise Monks who first offered guidance on the matter were concerned that off-site links may not be long-lasting.

IOW, I think you can sum up these observations as a call to "write a better tease" ...
        and, that said, yes, I, for one, find this so interesting¹ as to be persuaded to upvote a post whose content seems (to me) in serious need of improvement.

Update:   ¹ Where the value of "interesting" is "how does the code handle the many edge cases?"

Sorry my message was lacking.

The module is currently available here: https://github.com/mla/time-ago

Namespace suggestions welcome. I also put it on PrePan http://prepan.org/module/nY5Y569jtrb

Some examples of what approximate means:

#!/usr/bin/env perl

use strict;
use warnings;
use Time::Ago;

my $hour = 60 * 60;
my $day  = 86400;

foreach (0, 65, $hour * 3.5, $day * 376, $day * 365 * 14.7) {
  printf "%10s secs: %s\n", $_, Time::Ago->in_words($_);
}
[download]

Output:

         0 secs: less than 1 minute
        65 secs: 1 minute
     12600 secs: about 4 hours
  32486400 secs: about 1 year
 463579200 secs: over 14 years
[download]

The precise rules are detailed on the github page.

You should offer to merge your code with Time::Duration. Maybe as a sub-module -- Time::Duration::Ago (sweet!)

Remember: Ne dederis in spiritu molere illegitimi!

Suggestion: although it deviates from the original (rail) version:

Change the singulars from "1 unit" to "a unit", at least for the minutes
(or change the 65 seconds to "about 1 minute").

This would be more consistent. And "1 minute" sounds more exact than it is :-)

Have you looked at DateTime::Format::Human::Duration? It's what I've been using for a few years now and I wouldn't turn to anything else unless it was similar + improved performance (DateTime stuff is relatively slow), and even then I might not because I like working with DateTime objects.

There is an example in timestamp manipulation and evaluation

Yes, I had seen that. It looked very similar to Time::Duration except that it's based on DateTime.

Here's a script comparing Time::Duration, DateTime::Format::Human::Duration, and Time::Ago for various durations.

#!/usr/bin/env perl

use strict;
use warnings;
use lib 'lib';
use DateTime;
use DateTime::Format::Human::Duration;
use Time::Ago;
use Time::Duration;

my $hour  = 60 * 60;
my $day   = $hour * 24;
my $month = $day * 30;

my @durations = (
  0,
  38,
  60 * 4,
  $hour * 3.8,
  $month * 7,
  $month * 23,
  $month * 28,
);

my $class = 'Human::Duration';
foreach (@durations) {
  my $dt1 = DateTime->from_epoch(epoch => time - $_);
  my $dt2 = DateTime->from_epoch(epoch => time);

  my $diff = $dt2 - $dt1;

  print "Seconds: $_\n";

  printf "%-25s %s\n", '  Time::Ago', Time::Ago->in_words($diff);

  print "\n";

  my $class = '  Human::Duration';
  printf "%-25s %s\n", "$class #1",
    DateTime::Format::Human::Duration->new->format_duration($diff);

  printf "%-25s %s\n", "$class #2",
    DateTime::Format::Human::Duration->new->format_duration(
      $diff,
      units => [qw/ years months /],
    );

  printf "%-25s %s\n", "$class #3",
    DateTime::Format::Human::Duration->new->format_duration(
      $diff,
      precision => 'years',
    );

  print "\n";

  $class = '  Time::Duration';
  printf "%-25s %s\n", "$class #1", Time::Duration::ago($_);
  printf "%-25s %s\n", "$class #1", Time::Duration::ago($_, 1);

  print "\n\n";
}
[download]

Output:

Seconds: 0
  Time::Ago               less than a minute

  Human::Duration #1      no time
  Human::Duration #2      no time
  Human::Duration #3      no time

  Time::Duration #1       right now
  Time::Duration #2       right now


Seconds: 38
  Time::Ago               1 minute

  Human::Duration #1      38 seconds
  Human::Duration #2      no time
  Human::Duration #3      no time

  Time::Duration #1       38 seconds ago
  Time::Duration #2       38 seconds ago


Seconds: 240
  Time::Ago               4 minutes

  Human::Duration #1      4 minutes
  Human::Duration #2      no time
  Human::Duration #3      no time

  Time::Duration #1       4 minutes ago
  Time::Duration #2       4 minutes ago


Seconds: 13680
  Time::Ago               about 4 hours

  Human::Duration #1      3 hours and 48 minutes
  Human::Duration #2      no time
  Human::Duration #3      no time

  Time::Duration #1       3 hours and 48 minutes ago
  Time::Duration #2       4 hours ago


Seconds: 18144000
  Time::Ago               7 months

  Human::Duration #1      6 months, 4 weeks, and 1 day
  Human::Duration #2      6 months
  Human::Duration #3      no time

  Time::Duration #1       210 days ago
  Time::Duration #2       210 days ago


Seconds: 59616000
  Time::Ago               almost 2 years

  Human::Duration #1      1 year, 10 months, 3 weeks, and 1 day
  Human::Duration #2      1 year and 10 months
  Human::Duration #3      1 year

  Time::Duration #1       1 year and 325 days ago
  Time::Duration #2       2 years ago


Seconds: 72576000
  Time::Ago               over 2 years

  Human::Duration #1      2 years, 3 months, 2 weeks, and 5 days
  Human::Duration #2      2 years and 3 months
  Human::Duration #3      2 years

  Time::Duration #1       2 years and 110 days ago
  Time::Duration #2       2 years ago
[download]

You can see that Time::Ago is much more lax in it's approximation, always returning just a single, rounded unit.

The use-case for this is when precision is not especially important. e.g., for when a comment was made on a website, etc.

The latest version of T::A on github is now using Locale::TextDomain for localization, and support has been added for handling DateTime::Duration objects directly.

Updated to use Locale::TextDomain for localization. French, German, Italian, Japanese, Russian, and Spanish translations have been added.

https://github.com/mla/time-ago