We store information in active directory such as a person's home number, address, etc... If you open a user in outlook and view their details, this information is visable to anyone. How can we make these hidden in outlook so that a normal user cannot view any users home phone number? We use the data in AD for other things and really would not like to have to remove the data from the users AD objects.

You can remove attributes from the Outlook details templates. Do an Internet search on Exchange details templates for more information. This is probably the simplest, but if someone wanted to use a tool such as an LDAP query tool they can still access that information. A more complicated solution would be to actually remove the permissions to read that attribute. I have never removed permissions to a specific attribute so I would recommend thoroughly testing that in a lab before trying it in production.