Dear Frank and Joseph
Thanks for your answers. I will write a document and send it to you very soon explaining the Persian typesetting needs but it might take a while since I do not have much time these days.
I actually before emailing the LaTeX list, researched a lot and talked to different people and we all believe that we should have a separate format of LaTeX at least in 2e version. I also wrote the xepersian package which you can find in CTAN. Let me clarify that my work is going to replace the other packages and systems providing Persian typesetting in TeX. Also please note that farsitex is a dead project and it is based on latex2.09 not latex 2e, so the main aim here is to write something which works with latex2e. I also agree that having a seperate latex format is difficult and time consuming but I have so much passion about Persian typesetting in LaTeX that will put all my energy for it. Also Polish and another language (which I do not remember) format of latex are avaliable. However, with your advices I need to think more about what I am going to do and consider all the challenges and see if it worth putting some time doing it and also talk to several other people to see what they think. but I hope we can provide such support in LaTeX 3.