Barry McKay at OTN - Persisting PHP5 Objects in Oracle:

"Storing objects in your database is not just a gimmick; rather, it is the final piece in the "developing entirely within the object-oriented paradigm" puzzle. It allows you to analyze, design, develop, and test using all the techniques that are so popular in traditional, large-scale, object-oriented programming—using approaches such as business objects, UML, and design by contract—seamlessly. This is a radical idea, but the Web development world is catching up to it."