Just few hours of the announcement of Gmail Offline -- Google Calendar's offline mode started rolling out. Just like the Gmail Offline, Offline Calendar works in Google Chrome and requires the installation of Chrome Web Store app to enable some advanced permissions. If you click the wrench icon and select "Offline", Google will ask you to install the app.
After installing the app, Google starts to save the events from your calendars to you computer. To customize the list of calendars that are available offline, click the wrench icon, select "Offline" and then "Offline settings".
When you are offline, most Google Calendar features are disabled: you can't create new events, edit the existing events, search your calendars or print your calendars. You can only view some of the events from your calendars and RSVP to existing event invitations. Google Calendar doesn't even save all the events from your calendars. When trying to find older events, Google Calendar showed this message: "Your offline calendar only contains events from Jul 21, 2011 to Jan 5, 2012".
"You can only use offline Google Calendar for one account, even if you use multiple sign-in. "To disable your offline access, click the gear icon and select Disable offline calendar from the drop-down menu. This will disable offline access and remove any data stored on your computer"," Google said.