There is an XML::Parser Tutorial in the Tutorials section (written by OeufMayo), also check the Book Reviews node on what Perl books score well, also Outside Links has some general links you might want to check. (ab)use Super Search ! :) Best way to learn it, is by diving right into that big pile of code, books, tutorials, etc :)
Good luck ! :)

Greetz
Beatnik
... Quidquid perl dictum sit, altum viditur.