Modifying Display Templates and additional attributes

Recently got a question about customizing the GAL and my previous post that talks about it: "HOW TO: Modify Display Template to make default email address appear in Address Book/GAL".

The new Details Template Editor in Exchange 2007 (in EMC | Tools) makes it much easier to modify templates and give your GAL the kind of look you want (short of adding that 5 Mb. purple bitmap file as a background and an extra-large company logo perhaps... :). Screenshots and more information about Details Templates can be found in Managing Details Templates.

So, you're trying to customize the properties pages of your address lists and want to add an attribute such as ipPhone. You don't see the attribute you're looking for. Can you add additional attributes to the list? Or should you? Dave Goldman explains in Adding attributes to the Exchange details templates.