How do you lookup and search the Exchange Global Address Book (GAL) when you're on the road, with only Over The Air wireless access on a Windows Mobile device? Or schedule a meeting with someone at work and include an internal resource like a conference room or projector, or even check to see when a colleague is next available with their Free/Busy information?
If its just searching the GAL - unless you've synched it down to your Outlook contacts (this is pretty much impractical in a large organisation) the only way has been to use OMA (Outlook Mobile Access) which is the WAP based access into Exchange 2003 (this was in Mobile Information Server 2002 EE previously with Exchange 5.5 and Exchange 2000 as well) This OMA access works well, but its always going to be limiting because of the nature of WAP - breadth access, not necessarily feature rich.
Now we've released a new Windows Mobile Powertoy called Microsoft Global Contact Access. With Microsoft Global Contact Access, you can use Pocket Outlook on your Windows Mobile-based Smartphone or Pocket PC Phone Edition to look up contacts in the Global Address List (GAL) on your corporate Exchange server.
You can also check your co-workers' schedules to see if they're free or busy, and add multiple recipients to a meeting request.
Even if you're away from your office you'll have all the information you need to connect with any co-worker in your organization, and send them e-mail or request a meeting.
It runs on Pocket PC 2003 and Smartphone 2003 and connects to your organisation through the Exchange 2003 OWA Front End Server. The FAQ is here.
This is a very cool horizontal app (everyone else is an email junkie too right?) that I've been using for 6 months and really does make a Windows Mobile a much more user friendly device for doing email on.
There's a blogcast (5 minute webcast demo) on how GCA works in my blog entry here... http://blogs.technet.com/eileen_brown/archive/2005/07/06/GCA_blogcast.aspx