As many of you have already discovered, a new workflow file type is available for sending calendar invitations! ICS files allow email recipients to easily see and accept events to their own calendar.
This workflow can be tested out with a simple scheduling sample application available here - just copy the app and try adding an event with your email included to receive an attached calendar invitation.
To create an email workflow that includes a calendar invitation, visit Behavior > Workflow and add a new workflow rule. Select an ICS ‘Attachment Content Type’ and create a template for that attachment.