One obvious condition is when one needs to have a script that does the same thing on multiple operating systems. After all, Windows, *ix, z/OS, VMS, etc all have different scripting languages.
The other condition is, of course, when it's easier to write the script in Perl, which is why I learned Perl, as opposed to trying to write something with significant logic in a BAT file.
emc
Information about American English usage here and here.
Any New York City or Connecticut area jobs? I'm currently unemployed.