Reza,
With the google transliteration solution out there (
http://www.google.com/transliterate/persian), I don't see need for doing this again.
Late 90's, I wrote
postchi.com for email (he site is not mine anymore). More recently and before google, there were
behnevis.com and
emonshi.com..
I think Behnevis.com is written in python but it is not open source.
emonshi.com is mine and is written in c# and .net and if someone likes to start an open source project, I'll contribute and release the code.
Thanks,
Saeed Darya