Yes, mod_perl only works with Apache. The original question didn't state anything about IIS so I assumed apache (I should have mentioned that assumption in my original post). I think its a safe bet that most perl users are using Apache instead of other web servers.

Of course, depending on how the script is called the user can set up his script on a separate, dedicated "hit counting" box running Apache (easy to repuppose an old PC as a linux box for this purpose in many environments) he would be set. Or maybe use the first of those new sun boxes they're getting to build a new hit-counter box. Good way to test the new hardware and you don't have to migrate the whole system to sun to get it to work.