I don't recommend working in a beta technology myself, though you may love it. However, if you pay attention to which are new language features and do the exercises in PHP 5, then I think Ed Lecky Thompson's book is quite good.
by Ed Lecky-Thompson, Steven D. Nowicki
April 2009, Paperback
That said, the most readable book I've found on PHP is Kevin Yank's book.
Build Your Own Database Driven Web Site Using PHP & MySQL
by Kevin Yank
(Paperback - June 19, 2009)
Whatever you can do or dream you can, begin it. Boldness has genius, power and magic in it. Begin it now.
-Johann von Goethe
When Two Hearts Race... Both Win.
-Dove Chocolate Wrapper
Chroniclemaster1, Founder of www.EarthChronicle.com
A Growing History of our Planet, by our Planet, for our Planet.