I went through this a couple of years ago with my employer. So before going before our product approval committee I called around and searched our servers for all Perl scripts currently in use (unofficially at that time). When they saw how many scripts (and how long) Perl had been used in critical points in applications and system administration they realized they had to approve Perl else essentially stop production on several applications

On the support issue I don't recommend referring to the P5EE group that ignatz referred to just yet. This is still very much at a discussion point and could very well backfire if you brought it to their attention right now. The Active State issue is compelling for management, however, after they saw how long Perl was being utilized without support that argument disapeared. You might want to point out that there is no one to support any .bat or .ksh scripts in your Enterprise either. If they still push the issue offer to start an internal Open Source/Perl support group! (I'm still working on this).

And don't forget that Perl is shipped standard with Solaris -- showing Sun's adoption seems to pull some weight as well.