Elegance is one of those elusive words and ideals that means different things to different people. To me, for instance, "elegance" means having a certain beauty; code that is effective, efficient, and somehow beyond that - that does something in a beautiful way (what's beauty?). There seems to be also a sense of the unexpected, as well. Some things are more or less obvious - you can anticipate the next step, see where you can drop some unneeded stuff; that's just workmanship (in my opinion). It's the difference between painting some water lilies, and Monet's Water Lilies. To me it's that feeling I sometimes get of "Yesss!" - just a sense of the rightness of the expression. Elegance seems to be like the US Supreme Court's definition of pornography. "Darned if I can define it, but I know it when I see it".
When it comes to Perl, I personally think many of the idioms and one-liners are sheer artwork - and many are (to my view) quite elegant.