I have a co-worker that insists on writing his shebang like this (and he's on windows!):

#!perl

Now - that isn't going to work. :P It just won't. It works with ActivePerl on Windows, because it effectively ignores the shebang. I can't shell script to save my life. I've tried. :( So I wind up requiring perl at every turn, but at least I follow your logic:

#!/usr/bin/env perl

Fact it, 99% of the perl code out there expects perl in /usr/bin, which is just plain FALSE, and in fact the FreeBSD port for perl places a symlink to /usr/bin acknowledging this fact, despite the default port install location being /usr/local/bin (unless overridden).

So...bleh. I'm just glad someone agrees with me. :)