I don't have many details yet but we are planning to synchronize our AD with a partner company. Not even sure what that means yet. We are running in Windows 2003 native mode and all but two of our DC's are Windows 2008 R2. I have no idea what the partner is running. I am guessing we just want to share our GAL with them so they can send email and book meetings more easily. Not even sure where to start. Is there anything native to Windows that can do this? Do I need to use Microsoft online services? Is there a good article that explains what we are trying to do?