"Much of the buzz surrounding PHP5 has focused on its new object-oriented syntax and capabilities, and comparisons with Java. While all that was going on, the promisingly named "Standard PHP Library" (SPL) extension quietly made its way into the core PHP 5 distribution.
Although work is still in progress, the Standard PHP Library's current offering significantly increases the chances of getting PHP developers to agree on something (thereby increasing the chances of code re-use). It may also make your cunningly constructed class interface very easy for other people to use, as the SPL extension makes it possible to "overload" basic PHP syntax and make objects look like normal PHP arrays.
In this tutorial, I'll introduce the functionality available with the SPL extension and PHP5 with just enough examples to get you started. Be warned: PHP5's syntax will be used."