If you do a little bit of work during development, you can ensure that your applications work with the version the current "latest" Perl - or better yet, based off of 5.6.1. It just seems like a huge, unecessary burden to make sure the client is using *your* version of Perl. If someone gave me an app + the Perl he wanted me to use, I most certainly no install his Perl...in fact, I'd just use my own rather than have multiple versions of Perl floating around on my machine (especially if it was a windoze box).