Christopher Jones has reviewed one of the first Oracle PHP books that has been published ("Easy Oracle PHP: Create Dynamic Web Pages with Oracle Data") in his latest blog post today.
The writing style of Easy Oracle PHP is very clear. The book is relatively short at 264 pages but it focuses directly on PHP-Oracle interaction and does not need to be longer (though everyone will always wish for more).
Some topics covered in the book include the basics of PHP, the OCI8 model, using PEAR, using ADOdb, and installing the PHP5/Apache/PEAR combo. Christopher's opinion of the good overall is good, but notes that the target it would best fit with is for developers coming from Oracle to PHP (but will work as well for those coming the other way).