There's a new document from the collection Microsoft IT Showcase - How Microsoft Does IT. This time they focused on mobile messaging, so they released Mobile Messaging at Microsoft: Improving Security, Manageability, and User Experience.
If you have not yet implemented the new mobile features available with Service Pack 2 for Exchange Server 2003, this is definitely a must read.
"Overview: Detailed discussion describing how Microsoft IT uses Exchange Server 2003 SP2 and Windows Mobile 5.0 with the Messaging and Security Feature Pack to improve how it does mobile messaging. By using these new technologies Microsoft IT was able to manage mobile devices more easily, better secure mobile devices, and enable end users to take advantage of a more richer mobile messaging experience."