In the meantime I've learned and worked with OO a bit more and I've come to see some of the benefits a bit better. The main benefit though is found in when you have multiple sites hosted on a single server. That is when you can create an application framework that has a central place in the include_path, much like PEAR.
PHP5 is supposed to bring even more support for OO ... so we'll see what happens then. I haven't dived into PHP5 yet...