First and foremost, SAS is a statistical software. If SAS is a statistics professor; Perl is a baby.

On the other hand, Perl is a much nicer general glue language. SAS has pretty good macros; it's not quite as good as a programming language, compared to Splus or R. (R is a really good free Open Source statistical software by the way; not as bloated as SAS.)

In general, you use Perl to automate stuff around your statistical work, which's best done by SAS

There're something that both SAS and Perl may provide, such as database access and management as well as web publishing.

Many software that come with web publishing turn out to have clumsy web publishing capability, yet the price tags are enormously high. In that case, you're better off using Perl to get the data from your software and publish the data using Perl.

There're many other things SAS provides. So, I'm not sure what else you're also comparing.

In short, Perl can complement SAS more than SAS complement Perl (in a sense that you probably won't be controlling Perl from within SAS). Yet you'll never do in Perl what you'll do in SAS, which is really good at what it's doing (for a dear price).