I've made two 'updates' to this post, but I'm going to let it fly for a bit, then I'm going to come back and edit in my updates into the post itself...

Update: In v0.02, we now skip over prereqs where the version is listed as 0 (zero). This signifies that any version of a prereq is acceptable. To disable this and display all prereqs even if the version is zero, use the ignore_any => 0 parameter. /update

Update2: I've updated the distribution (v0.05) to install a binary, checkdep, so that you don't have to write your own to use the library:

Usage: checkdep PAUSEID [options]

-a|--all        Work on all dependencies, not just the author's
-m|--module     String; Work only on a specific distribution. (eg: Moc
+k::Sub)
-z|--zero       Include dependencies listed with a version of zero
-h|--help       Display this help screen
[download]

/update2

I've got quite a few CPAN distributions that require one another, and it's gotten to the point that it's very easy to forget to bump prereq versions before uploading a new release to the CPAN.

As a stopgap, I wrote Module::CheckDep::Version (may not be indexed yet). What this module does is using MetaCPAN::Client, fetches all distributions by author, pulls out all prerequisite distributions and the version of it that your distribution has listed, checks if there's a newer version of it, and lists out the ones that need a bump in the prereq's version.

The most basic of runs takes a single parameter, a PAUSE ID (CPAN username), and lists the discrepancies of prereq version mismatches for that author's own prereq distributions *only*. Here's an example of that:

use warnings;
use strict;

use Module::CheckDep::Version qw(check_deps);

check_deps('STEVEB');
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Here's the full output of that function call:

    RPi-ADC-MCP3008:
        WiringPi::API:
            2.3608 -> 2.3612
        RPi::WiringPi::Constant:
            0.02 -> 1.00

    App-RPi-EnvUI:
        WiringPi::API:
            1.04 -> 2.3612
        RPi::DHT11:
            1.01 -> 1.02
        Logging::Simple:
            1.01 -> 1.04
        RPi::WiringPi::Constant:
            0.02 -> 1.00
        Async::Event::Interval:
            0.00 -> 0.03

    RPi-BMP180:
        RPi::WiringPi::Constant:
            0.02 -> 1.00
        WiringPi::API:
            2.3608 -> 2.3612

    Wrap-Sub:
        Devel::Examine::Subs:
            1.63 -> 1.69

    RPi-I2C:
        WiringPi::API:
            2.3609 -> 2.3612

    RPi-DigiPot-MCP4XXXX:
        RPi::WiringPi::Constant:
            0.02 -> 1.00
        WiringPi::API:
            2.3608 -> 2.3612

    RPi-WiringPi:
        RPi::I2C:
            2.3602 -> 2.3603
        RPi::LCD:
            2.3601 -> 2.3603

    Devel-Trace-Subs:
        Mock::Sub:
            1.01 -> 1.07
        Devel::Examine::Subs:
            1.61 -> 1.69

    Test-BrewBuild:
        Plugin::Simple:
            0.06 -> 0.07
        Logging::Simple:
            0.07 -> 1.04
        Test::BrewBuild::Plugin::Author:
            0.02 -> 0.03

    RPi-SPI:
        WiringPi::API:
            2.3608 -> 2.3612

    File-Edit-Portable:
        Mock::Sub:
            1.06 -> 1.07

    WWW-ProxyChecker:
        WWW::FreeProxyListsCom:
            0.00 -> 1.005

    RPi-DAC-MCP4922:
        WiringPi::API:
            2.3608 -> 2.3612
        RPi::WiringPi::Constant:
            0.02 -> 1.00

    RPi-Pin:
        WiringPi::API:
            2.3609 -> 2.3612

    Devel-Examine-Subs:
        Mock::Sub:
            1.06 -> 1.07
[download]

Using the all => 1 param, we'll check against *all* prereqs, the author's own ones and those of any other author. If it's listed as a dependency, we'll check it:

check_deps('STEVEB', all => 1);
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Example (snipped) output:

Devel-Examine-Subs:
    Test::Trap:
        0.00 -> v0.3.2
    ExtUtils::MakeMaker:
        0.00 -> 7.30
    Carp:
        0.00 -> 1.38
    Data::Dumper:
        0.00 -> 2.161
    PPI:
        0.00 -> 1.236
    Mock::Sub:
        1.06 -> 1.07
    Data::Compare:
        0.00 -> 1.25

Geo-Compass-Variation:
    ExtUtils::MakeMaker:
        0.00 -> 7.30

RPi-LCD:
    ExtUtils::MakeMaker:
        6.72 -> 7.30
[download]

You can look up only a single distribution instead of listing all of them (this works with all => 1 as well):

check_deps('STEVEB', module => 'RPi::WiringPi');
[download]

Output:

Pi-WiringPi:
    RPi::I2C:
        2.3602 -> 2.3603
    RPi::LCD:
        2.3601 -> 2.3603
[download]

You can request the data back (a hashref of hashrefs) instead of displaying it to STDOUT:

my $data = check_deps('STEVEB', return => 1);
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...and finally, you can send in a code reference to handle the data within the module instead of getting it returned or printed. This sub can do anything you want it to. You get passed a single parameter, a hashref of hashrefs, same as with the return functionality:

check_deps('STEVEB', handler => \&my_handler);

sub my_handler {
    my $data = shift;

    for my $dist (keys %$data){
        for my $dep (keys %{ $data->{$dist} }){
            my $dep_ver = $data->{$dist}{$dep}{dep_ver};
            my $cur_ver = $data->{$dist}{$dep}{cur_ver};

            print "$dist has dep $dep with listed ver $dep_ver " .
                  "and updated ver $cur_ver\n";
        }
    }
}
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Sample output:

App-RPi-EnvUI has dep Async::Event::Interval with listed ver 0.00 and 
+updated ver 0.03
Devel-Trace-Subs has dep Devel::Examine::Subs with listed ver 1.61 and
+ updated ver 1.69
Devel-Trace-Subs has dep Mock::Sub with listed ver 1.01 and updated ve
+r 1.07
RPi-WiringPi has dep RPi::LCD with listed ver 2.3601 and updated ver 2
+.3603
RPi-WiringPi has dep RPi::I2C with listed ver 2.3602 and updated ver 2
+.3603
[download]

I was going to hook this into an automation script using other tools I have written, but I just don't have the time. Just knowing what needs to be updated is fine for me for now.

Next version will have the ability to optionally skip prereqs that the author has set to 0 (ie. any version is acceptable).

As always, have fun!