it doesn't care about what binary the script claims should be invoked

Interestingly enough, it *does* care about the name of the binary, but only to the extent that it matches /perl/i.
If you try running a script that begins with #! xxxxx (where 'xxxxx' stands for any string of characters that does *not* match /perl/i) then all you'll get is a "Can't exec xxxxx ...." error.

This wasn't always the case, but has been since at least perl-5.8.0

Update: And if 'xxxxx' happens to be the name of a non-perl binary that *does* get found, then things might (or might not) get a little crazy:

C:\_32\pscrpt>type try.pl
#! gcc -w
print "ok\n";
C:\_32\pscrpt>perl try.pl

C:\_32\pscrpt>try.pl: file not recognized: File format not recognized
collect2: ld returned 1 exit status

C:\_32\pscrpt>
[download]

Cheers,
Rob