If you run Apache on your windows machine and you have installed Perl at C:\usr\, then Apache will find the perl executable at /usr/bin/perl. So this shebang is necessary and correct.
I run Apache on my Windows machine. Perl is not installed at c:/usr/ and none of my scripts use the she-bang line and still it works. So it may be correct but it sure is not necessary.
CountZero
"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law