hi
Are you using meeting workspace?
If you create a new Meeting Workspace site, and send a meeting request with a link to the site, the attendees are automatically assigned to the Contributor site group and are added to the site as users with rights to read and write to the Meeting Workspace site. As the meeting organizer, you are assigned to the Administrator site group. If there is a problem with granting rights to an attendee automatically, you will get a message with instructions on where in the Meeting Workspace site you can add the attendee as a user.
A Meeting Workspace is a Web site for centralizing all the information and materials for one or more meetings. Before the meeting, use a workspace to publish the agenda, attendee list, and documents you plan to discuss. During or after the meeting, use the workspace to publish the meeting results and track tasks. Send a meeting request to invite people to the meeting. In the meeting request, include a hyperlink that goes to the workspace where invitees can learn the meeting details and see the materials.
Although Outlook updates the Attendees list in a Meeting Workspace site, it does not automatically assign permissions to the attendees to access the Meeting Workspace site. Whether rights are granted automatically or not depends on the type of your Meeting Workspace site.
http://support.microsoft.com/default.aspx/kb/831055
Irene
