ics Sync Desktop is a desktop tool that can sync web calendars, such as, Google Calendar, Windows Live Calendar, or any other calendar that supports .ics format, with Windows Mobile Devices. Not only does it provide a simple interface for quick synchronization but also supports sync to multiple devices.
Officially, it supports Windows Mobile 5, Windows Mobile 6, and the older Windows Mobile 2003. There is no word if it supports the upcoming Windows Phone 7 yet (if you are a developer, we would be glad if you can test it out and let us know).
Just like the program supports syncing of calendars with multiple devices, it also supports multiple calendars which can be added under in the Calendar List. Once the device is paired with your computer, all calendars under the Calendar List will be synchronized.
The usage is easy, first you need to pair the device, add calendars, and hit Sync to synchronize it with the device. The video below gives a good step-by-step demonstration of the whole procedure.
The only requirement is that you should have ActiveSync / Windows Mobile Device Center and .NET Framework 3.5 (which is already installed if you are running Windows 7).