In this post I discussed Syncing Windows Mobile with Google Calendar using ActiveGCSync. Now I have found a way to sync your calendar using regular Active Sync.
Google has a new synchronisation service called Google Sync. The service is only available for Google Apps users so you need to set up a new calendar in Google Apps. Google Apps is still free up to a maximum of 50 users, but the registration page is difficult to find. You can find the registration page here.
Here's how I set up my calendar synchronisation:
1. Register a new account for Google Apps
2. Open Domain Settings, set Control Panel to "Next generation (US English only)"
3. Open Service Settings and enable Google Sync
4. Enable Google Calendar for your account
5. Set up ActiveSync using this guide
If your PDA was already in sync, this is all you needed to do. Use the Google Apps calendar from now on. If you need to export the appointments from your old Google calendar use this guide and this guide to import them again.
So far this has been working great, I'm getting less errors than ActiveGCSync used to generate. Now let's see when Google will allow ActiveSync to work with Gmail.