Penguin uses the following modules:

1.  Graham Barr's IO:: module (IO::Socket, IO::Filehandle, etc.)

    Penguin uses this to implement the TCP/IP channel.  You
    don't actually need this if you don't plan to use TCP/IP
    with Penguin (i.e. you're writing Penguin applets and
    relying on the web browser/server to move them around).

    All recent versions of Perl include the IO module.  I
    strongly recommend upgrading your Perl if you don't have
    an included IO.

2.  PGP.  Well, it's not exactly a module so much as an
    entirely separate cryptosystem.  Any version after 2.6
    should work.

    The PGP support shipped with Penguin does not do any
    kind of encryption, and only uses PGP to digitally sign
    code.

3.  Malcolm Beattie and Tim Bunce's Safe module

    This is distributed with recent Perls.  If you don't
    have it, get the latest Perl.

In the future, I expect all of this stuff to be bundled in
such a manner that you don't have to worry about it any
longer.