There's a new book that introduces the Perl programming language. It was written with the participation of the community. The book is also available freely.
Modern Perl book on the publisher's site: http://www.onyxneon.com/books/modern_perl/index.html
Free PDF version of the book (A4): http://www.onyxneon.com/books/modern_perl/modern_perl_a4.pdf