Google has announced the availabilit of a new option in Google Calendar: read-only offline access to the calendars using Google Gears. “Calendar keeps you on time, even when you're not online. Offline Calendar allows you to access your events through your browser without requiring Internet access. It's perfect for flaky connections or for when you're in between meetings and have no idea where you're supposed to be next. Note that while offline, Calendar will be read-only - it will not be possible to create, edit, or delete events,” Google help page.
To enable offline in Calendar: Sign in to Calendar. In the upper right-hand corner of your account, next to your username, there will be a new 'Offline Beta' link. Click this link to start the offline synchronization proces.