Hi there!
This is not possible out-of-the-box. Here are a some suggestions for solutions.
- You can create the calendar activities using Appointments and render the calendar in a report.
- You can also use the Outlook calendar functionality and create a plug-in that sends meeting requests to that calendar such as is described in this blog.
- www.powerobjects.com/.../sending-meeting-requests-with-microsoft-dynamics-crm
- You can create a custom screen to display the calendar.
- You can set up a SharePoint site for each project and use the calendar function there--possibly integrate that with CRM so it is visible in both places.
None of these solutions use the built-in toolset; instead they require advanced skills for reporting and extending CRM.