Within last a few months me and two of my friends have started working on implementing Persian Calendar for SharePoint 2007. Now after more than 6, 7 month work on this we have the Persian Calendar implemented in SharePoint 2007.
One of the most important point about this package is that youwil stil have your Hijri calendar while you can use Persian Calendar too. Also it 's possible to develop web parts which can use Sharepoint Persian Calendar.
While Microsoft is not supporting Persian calendar on Sharepoint officialy, Now we are negotiating to transfer this technology, with some of the most active companies which are working on providing SharePoint stuff in Iran and Middle East.
You can find out more news about Sharepoint 2007 Persian Calendar on my web site : http://www.tabatabaei.info/