Simas Toleikis has posted an interesting idea for a validator that would look at the incoming source of an application/script and determine what the requirements for it might be.
How about creating a PHP code validator? Got this idea by looking at tokenizer and reflection extensions. I doubt I will find the time to work on this myself but then someone else might be interested to pick it up. From user's point of view there will be a form made of a large textarea box and a single file upload input. One could paste code snippet on that textarea or upload a ZIP'ed source code archive (or a single .php file) for validation.
His proposed result would show a list of "Required Extensions", PHP versions, E_STRICT compatibility and possibly total lines of code in the project. He points out a few issues that might pop up in writing such a tool such as the requirement for it to be able to use the tokenizer extension itself (a sort of catch-22 since it's not always installed).