The book Advanced PHP Programming is out, by George Schlossnagle. Looks like it might be pretty interesting; there’s certainly a scarcity of good PHP books that cover advanced topics—most of them are targeted at the beginner and the basics, and don’t have anything to offer me.
(Quick disclaimer: some of the Wrox books actually look like they might be decent, but I haven’t had my hands on a Wrox PHP book since the first couple they published.)
There was a time when I wanted to write a PHP book. It was going to be an advanced book, called “PHP Secrets” and cover all sorts of topics. I never really pursued it, though, largely because of a general disillusionment in the computer book industry: you spend a year or more writing a book on a subject, and by the time it gets published it’s obsolete.
Thinking about it now, though, maybe a better venue for such a thing would be online, like what Mark Pilgrim did with his Dive Into Python book. That might be kind of cool; a live work-in-progress that I could (theoretically) keep up-to-date. Hmmm.