I think this is a great idea. I would love to be able to share the marketing calendar with staff who aren't using HubSpot, but could benefit from the calendar.
Second this! Not all of our employees use HubSpot, so they check Google Cal for the marketing schedule. I would love to be able to use the HubSpot calendar tool & have tasks/items sync to that Google Cal for internal visibility. As it is, I'm not going to update both calendars, so will continue using Google predominantly until this is available.