The user dashboard in 1.9 and prior versions displayed ALL scheduled activities if user had "administer CiviCRM" permission. This is "broken" in 2.0.
1. Dashboard query needs to filter by status and only retrieve activities with status = Scheduled. This is the behavior in prior versions and facilitates the intended use of the Dashboard as a To Do list.
2. Dashboard should retrieve scheduled activities for ALL contacts if user has "admin CiviCRM" permissions. This flag was retained in param for the functions which get the count and rows - but the query isn't modified by the flag as it should have been...
Compare these functions in 1.9
CRM_Contact_BAO_Contact:: getNumOpenActivity and getOpenActivities
.... to these in 2.0
CRM_Activity_BAO_Activity::getNumOpenActivity and getOpenActivities