PHP JAVA or maybe another??

I am planning to launch a web based charting system. My concern is which language would be appropriate? I would like it to be as close to C++ as possible as I might like to convert it to a desktop application later or even change it to run on the mac (as I think mac's use Obj-C) and iPhone/iTouch/iPad.

My question is what would be the best way to do this?

You can write portable desktop applications in Python, so my choice would by Python.

The next best choice would be Java, because if you later want to convert it into something like C++ you should have witten the prototype in a statically typed language also. Java would be easier to port to C++ than python, ruby or php or another dynamically typed language. And you could even make the Desktop app completely in Java also and have to port nothing at all.

Another option would be to write the web app in C++ (or any other systems programming language) that is also suitable for portable Desktop applications, so you wouldn't have to port anyting.