How can I add an ICS meeting automatically to the Organizer's calendar?

It looks like this issue might be solvable by applying a HotFix to Outlook.

  • Description of the Outlook 2007 post-Service Pack 1 hotfix package: January 28, 2008

It seems it could be related to setting ExtractOrganizedMeetings in the registry. Worth a try.

See:

  • You cannot accept an invitation that is in a third-party calendar format in Outlook 2007
  • As the meeting organizer, you cannot accept a meeting request in Outlook 2007 if you used a public Calendar for the meeting that you created