Users of Windows Phone 7 (WP7) devices may experience the following issues when synchronizing calendar events.

Recurring Events - There is no way to set an end date for a recurring event when creating it on a WP7 device.  The event must be edited on the server to specify an end date.

Meeting Invitations - Attendees being added to a calendar event must first exist in the device contact list (People) with an email address.  If an attendee is not in the device contact list or is in the list without an email address, he/she cannot be added to the invitation.