in reply to Should I upgrade my "Learning Perl" Book?
Well, I don't want to sound like an advert for O'Reilly, but another option is their Safari bookshelf. Costs me $15 a month and I have instant access to all the O'Reilly books (as well as books from other publishers such as Addison Wesley and Microsoft Press). The books are updated whenever errata is found or a new edition comes out. It's great for when I need some specialized knowledge for a project, but don't want to buy a whole book for just a few pages of explanation.
There are a few restrictions such as only 10 books at a time on the shelf and you have to keep a book on the shelf for 30 days. You can even buy tokens that allow you to download a chapter in PDF form, great for getting appendices that contain command syntax. If you really must have the paper version, you can order it at a discount.