Seconded. As long as you already have some programming experience (in
whatever language), then php.net should have all you need to learn PHP.
Thirded. Oh, and i was the firsted one, it seems. hmm.
My findings are that:
1) PHP.net has fantastic documentation
2) PHP.net has a very good newbie turorial
3) PHP.net is searchable (unlike a book, which, GoogleLibrary aside, has
only an index)
4) PHP.net is nearly always up-to-date.
I *NEVER* use a book to look up functions or other reference information
on PHP. I even teach a PHP class and must use a book for the class
(because that is what is expected) but the first thing I teach the class
is how to use PHP.net and throw away the book.
Google, Google Groups, and PHP.net are all you'll ever need.