Nice
I'm not a fan of classes that take input other than what is fed to it (i.e. the use of anything other than what I pass to it. Offending items such as the use of $_GET within the class :p)
It may also be worth noting a lot of that will have to be edited for use on PHP5 if/when it becomes the standard (just like any class of course)
Should this be in the Snippets forum?