Well, it's exactly like Perlbrew, but for Windows. It allows you to have any number of Perl installations installed, without touching the system perl.

...and do things like:

berrybrew exec cpanm Module::One
[download]

...which will install the module on ALL installed versions. Or:

berrybrew exec --with 5.22.1_64,5.24.0 cpanm Module::One
[download]

to install on only select vers.

For example, say you need a module but want to check which version of Perl it'll run under, before deciding on a version to install system-wide to a number of Windows machines:

>berrybrew exec cpanm Log::Simple

Perl-5.24.0_64
==============
--> Working on Log::Simple
Fetching http://www.cpan.org/authors/id/M/MO/MOUNS/Log-Simple-1.8.tar.
+gz ... OK
Configuring Log-Simple-1.8 ... OK
Building and testing Log-Simple-1.8 ... OK
Successfully installed Log-Simple-1.8
1 distribution installed


Perl-5.22.1_64
==============
Log::Simple is up to date. (1.8)


Perl-5.22.1_32
==============
--> Working on Log::Simple
Fetching http://www.cpan.org/authors/id/M/MO/MOUNS/Log-Simple-1.8.tar.
+gz ... OK
Configuring Log-Simple-1.8 ... OK
Building and testing Log-Simple-1.8 ... OK
Successfully installed Log-Simple-1.8
1 distribution installed


Perl-5.18.4_32
==============
--> Working on Log::Simple
Fetching http://www.cpan.org/authors/id/M/MO/MOUNS/Log-Simple-1.8.tar.
+gz ... OK
Configuring Log-Simple-1.8 ... OK
Building and testing Log-Simple-1.8 ... OK
Successfully installed Log-Simple-1.8
1 distribution installed


Perl-5.14.4_64
==============

--> Working on Log::Simple
Fetching http://www.cpan.org/authors/id/M/MO/MOUNS/Log-Simple-1.8.tar.
+gz ... OK
Configuring Log-Simple-1.8 ... OK
Building and testing Log-Simple-1.8 ... OK
Successfully installed Log-Simple-1.8
1 distribution installed

Perl-5.14.4_32
==============

--> Working on Log::Simple
Fetching http://www.cpan.org/authors/id/M/MO/MOUNS/Log-Simple-1.8.tar.
+gz ... OK
Configuring Log-Simple-1.8 ... OK
Building and testing Log-Simple-1.8 ... OK
Successfully installed Log-Simple-1.8
1 distribution installed
[download]

That is a good and well-explained example of a real world problem and the real world solution using berrybrew.

What sent me down the road of forking berrybrew and modifying it was writing Test::BrewBuild... you can set up Unix Perlbrew and Windows berrybrew servers wherever you want, and using Test::BrewBuild and its utility components, send module builds to these remote servers, and they will all test your module against all of their installed versions of Perl, and return the results:

# within a module directory... 

bbdispatch -t localhost -t 192.168.252.90 -t 192.168.252.96 -t 192.168
+.252.95
 
192.168.252.95 - x86_64-linux
 
5.22.1 :: PASS
 
192.168.252.90 - MSWin32-x64-multi-thread
 
5.18.4 :: PASS
5.22.1 :: PASS
 
localhost - MSWin32-x64-multi-thread
 
5.22.1 :: PASS
 
192.168.252.96 - amd64-freebsd
 
5.22.1 :: PASS
5.23.7 :: PASS
5.8.9 :: FAIL
5.10.1 :: FAIL
5.18.4 :: FAIL
[download]