Great reply to an important question. I have only minor additions.

I've found things like Perl2exe to be too "clever" and thus not overly hard to break. I find the idea of identifying which files are actually used by a script and packaging them all up together to be very handy. But I find it a bit silly to package them all up into an executable that tries to run the script when you run it. I'd rather just pack them up into a (possibly self-extracting) zip file that expands to the script and a subdirectory contain the bits of Perl you need for it. By doing this, you won't break anything (other than failing to identify some of the required files, which is why they invented testing).

For the Perl scripts I've distributed, the solution has always been to include a full version of Perl w/ any needed extra modules and give the recipient the option of installing that or maintaining their own copy of Perl if they prefer (or just send the script, of course, but that isn't the kind of case we are discussing here).

Packaging up a version of Perl for a specific operating system is nearly trivial (you use zip or tar+gzip).

Under Win32, the one minor problem is that if you want to allow the recipient to install more modules then you have to update Config.pm based on where the recipient unpacked your archive. But that code isn't hard to write and prewritten versions can be found.

Under Unix, the (perhaps larger) additional problem is allowing the recipient to specify what directory Perl gets installed into. I've previously built Perl such that the @INC paths were rediculously long and then would patch the perl executable to replace these based on the install location chosen. Quite a hack, but it worked. /:

For larger subsystems, having a "private" copy of Perl included in the subsystem makes a lot of sense because Perl isn't really that big compared to most subsystems and doing this makes your QA department's life manageable.

Perl6 is intended to support "compile to Java engine" so you could ship your Perl6 applications as "compiled Java".