"Windows Mobile Device Center is the new name for ActiveSync in Microsoft® Windows Vista™, and provides overall device management features for your Windows Mobile-based devices in Windows Vista, including smartphones and pocket PCs. All of the features previously available in ActiveSync are available in Windows Vista, including synchronization and setting up your partnership. However, most of the user interface has changed in an effort to enhance your ability to easily and intuitively find device-related tasks and improve the overall usability of those tasks. Please note that only a portion of Windows Mobile Device Center is included in this release of Windows Vista. This primarily includes core device connectivity components, which allows the operating system to recognize that a Windows Mobile-based device has connected and load the appropriate device drivers loaded and services. Included with this is our Windows Mobile Device Center base application that enables some basic functionality, including the ability to browse the contents of your device, use desktop passthrough to sync with Microsoft Exchange, and change some general computer and connection settings."
Finally we leave ActiveSync with the next major Windows version. This article outlines a bit more about the device center and its proposed features. If it works better than AS in some areas, that's all I care about!