Microsoft recently released yet another ActiveSync Beta - this time for ActiveSync 4.5.
With the introduction of Windows Mobile 5.0, ActiveSync 4 is the only way to get the latest Windows Mobile devices synced with Windows-powered PCs and Microsoft Outlook - right out of the box.
ActiveSync acts as the gateway between your Windows-powered PC and Windows Mobile-powered device, enabling the transfer of Outlook information, Office documents, pictures, music, videos and applications to and from your device. In addition to synchronizing with a desktop PC, ActiveSync can synchronize directly with Microsoft Exchange Server 2003 so that you can keep your E-Mail, calendar data, tasks and contact information updated wirelessly when you're away from your PC.