Thanks for your question thomas.
GrooveIT! for Outlook allows you to export events from Outlook to Groove. This action can be done manually / "on demand".
Your choose an event, click the "Send to Groove" button and use the wizard to choose in wich workspace and tool you would like to sent this event. In this case, it is an export. There's no update in Groove if you modify or delete your event in Outlook.
On another hand, you can also create a GrooveIT! rule. A rule is a mean to link a Outlook container (calendar, tasks list, email folder...) to a Groove workspace and tool. If you create a link on a calendar, each time you add an event in Outlook, this event is also exported to Groove. Each time you modify an event, it is also updated in Groove. Please note that, at this stage, if you delete an event in Outlook, it is not deleted in Groove.
GrooveIT! for MyCalendars will allow you to have a single consolidated view of several calendars. You will be able to use Outlook calendars and Groove calendars.
Hope that helps