Good Question and here's the full answer FWIW
CL USB Sync adds it's own Calendar list. Originally this was intended as a stopgap In our initial development push we could not get consistent results adding data to the Droid Calendar.
Google has not released an API for Android Calendars as they have for Contacts. We can write to a provider in the Calendar, but providers are undocumented. Google has released source code for Android, but each carrier and manufacturer modifies it, and the modified versions are generally not available. At CompanionLink we don't hack or deconstruct other people's code. If an API doesn't work, we generally innovate our way around the problem.
There are inconsistencies between Android versions in Calendar, so even two devices with identical version numbers; G1 and Hero for instance, have different Calendar structures. Calendar data is linked to Accounts; i.e. a data source like Google. One source is Google, and another source is Microsoft Exchange ActiveSync. The danger of using an undocument API is that an inline update, like Droid 2.1 may interfere with data, or worse, damage data in a way it get sync'd back to the office computers damaging corporate data at the source. We've concluded that Account management in Android Calendars is incomplete for any data source that is not Google or Activesync. If this is truly the case, we'll see that no 3rd party App will ever be able to write data to the onboard Calendars in a dependable way.
So it is with sadness at the inadequacy of the platform, and also annoyance over the time and resources we have spent, that we have finally ended our pursuit.
All CompanionLink solutions in the future will be centered on a Calendar App replacement, with structures that match Recurring Events and Exceptions as modeled in Google and PC Programs like Outlook. We will support category management, colors, free/busy flags, invites, attendees and locations will all match what PC users expect, without regard to Android version, manufacturer or carrier additions. Our sole contact with the onboard Calendar will be to grab data from it, and update that data if it changes. We will not add accounts or add records, and will keep our contact at a minimum to avoid any disruption to the fragile sync systems that exist for the onboard Calendars.
Calendars are important. We try to do a good job. We can't do a good job if the platform is too fragile to handle real-world customers. It will be a considerable task for us to build a complete Calendar App from scratch. Look for a full release of our new Calendar App from CompanionLink by April 1, 2010.
Wayland Bruns, CTO
CompanionLink Software, Inc.
www.compaionlink.com