Admins may add calendars to the Intranet from the Network Admin screen.
Go to My Sites>Network Admin>Dashboard, then Intranet>Settings>Calendar(tab)
On this page, you'll see fields for a calendar title and embed code. Multiple calendars may be added.
Please note, only Google Calendar embed codes may be used at this time.
Office user profiles also contain a field for a calendar embed code. This allows different offices to display a single office-specific calendar