I think that something titled "Understanding Perl" could do well. My notion is that it would set out the general rules that perl follows with lots of explanation, examples, and a careful review of exceptions to the rules.

It should include clear exposition of:

1. perl contexts
2. lists
3. calling conventions
4. unix, as expressed in perl's design
5. internals (badly needed now that the panther doesn't cover it)

That's only partial, more suggestions are invited.