Schema updates for AD it is something which gives most of customers I'm working with a creeps. They don't like it, they don't want to do this.
I hope that just published document titles Structured Active Directory Schema Management at Microsoft will let them to overcome the fears and prepare schema management process for their organizations.
For some time I've heard that this document is being written but when I've read it now it looks like this is something more then I've been expecting. Besides technical aspects it described entire process, and this word seems to be most important. You have to have a process if You want to do such things effectively in bigger environment.
Nice reading, enjoy it. For those who prefer to watch there is also a corresponding webcast.