As the results from our recent PHP survey show, PHP 4 is really not a factor anymore. Even if you are currently running PHP 4, odds are that its very easy to switch to PHP 5. In this day and age, there is absolutely no reason not to run PHP 5. PHP 4 is no longer supported by Zend, is slower, and is potentially a security risk, so you should be running at least PHP 5.2 at this point.
What this means for RocketTheme is that we will no longer be supporting PHP 4 in any of our templates, themes, extensions etc. This means we can write better, faster code without having to make the compromises we traditionally do to ensure PHP 4 compatibility.
More information regarding the survey can be found is this blog post: