Make an outlook rule for appointment invitations

Yes, it is possible. I tested this myself in Outlook 2010.

1. Create a new rule for when a message arrives.
2. Under the Step 1 on the conditions page, select uses the form name form
3. Under Step 2 on the conditions page, click form name
4. Choose Application Forms rather than Personal Forms, and then choose the forms that apply. Definitely select the Meeting Request form, and you also may wish to consider:
   • Accept Meeting Response
   • Appointment
   • Decline Meeting Response
   • Meeting Cancellation
   • Tentative Meeting Response
5. On the next page of the wizard, select move it to the specified folder, and in Step 2, choose the folder.
6. Finish the wizard

For Outlook for web (and the new desktop Outlook), you need to add a "Type" condition for when an email has the type "Invitation".