Interesting Mobile 5.0 APIs are being released - you'll get them in ROM and hence do not have to be deployed to the target by your setup programs. To code against them, you need to download the free Windows Mobile 5.0 SDK which installs the six libraries that you can reference from your Visual Studio 2005 Smart Device project, so you can use the namespaces and types and gain access to the new features. The SDK also provides Windows Mobile 5.0 emulators for use from within Visual Studio 2005. These class libraries are (in no particular order):

• Microsoft.WindowsMobile.Telephony.dll: make phone calls programmatically.
• Microsoft.WindowsMobile.Forms.dll: Contact Chooser, Picture Picker and Camera Capture dialogs.
• Microsoft.WindowsMobile.dll: it is not used directly in your code and is only necessary when referencing the Status and PocketOutlook dlls described next.
• Microsoft.WindowsMobile.Status.dll: this powerful library provides an easy to use generic way for accessing device state and for getting notified when device state changes (over 100 system properties), even when your application is not running.
• Microsoft.WindowsMobile.PocketOutlook.dll: wraps the Pocket Outlook Object Model (POOM) for interacting with Personal Information Management (PIM) items: appointments, contacts and tasks. This is also the place to look if you want to programmatically send SMS and email messages or even intercept SMS messages as they arrive.
• Microsoft.WindowsMobile.Configuration.dll: useful for processing or testing device XML configuration files e.g. for provisioning a device. Essentially a managed wrapper for DMProcessConfigXML.

Now that your appetite is whetted, browse the online documentation for more details and install the Windows Mobile 5.0 SDK to have a play in your favourite language (C# or Visual Basic):

• Windows Mobile developer site.
• UK MSDN Nuggets page