It's also easier to add events in the calendar without going to the site. If you enable the alerts in Google Desktop, you can be notified about the events. Even if your Internet connection goes down, you'll still be able to see your calendar and get alerts.
The gadget requires Google Desktop 4, which was also updated to version 4.2006.825. If you already have the gadget, you need to download the new version.
Related:
Add events to Google Calendar faster
Google Persistent Memory