As I am sure that many here would agree, I will put in my two cents worth (about 1EUC) and say that O'Reilly makes a good product, no matter what the language. I know this sounds like a commercial, but I have purchased quite a few of these books. I have been dissapointed in none of them.

UPDATE: I put this here as to back up what simonm said in the previous Re: Seeking your recommendation - Perl resources.