I want to upgrade to PHP 5.3.3 but I believe Zend Optimizer is not available yet for this version of PHP.
I currently have Zend Optimizer on PHP 5.2.10 but I'm not sure if I'll miss it or not?
Can someone tell me what the benefits of Zend Optimizer are and if they are worth staying on PHP 5.2.10 for?
The main benefit of Zend Optimizer is code obfuscation. If you're using software that requires it (as a lot of closed source PHP code does) then you need it. If you're just using it for speed, APC is better in my experience.
zend optimizer has been updated and you can download and install it using the Zend Guard:
http://www.zend.com/en/products/guard/downloads