Outlook iCal does not work?
I think this is resolved. After researching prior problems with icals, I found this reference: https://stackoverflow.com/questions/15084236/icalendar-does-not-create-an-event-for-organizer 

By changing the METHOD: REQUEST to METHOD: PUBLISH in templates/CRM/Activity/Calendar - Outlook users are essentially inviting themselves to their events (and the possibility to including others who are not Civi users).

Note: However, it looks like the notes aren't being pulled into the ical, and I'm not sure if this should occur or not.