Is there a event which is raised when permission of a sharepoint list item is changed. For instance permission is granted or revoked on a list item
Actually, there is no build in permission-relaited events for list/web/site/users/groups/etc.
As a "might be solution" you can use SPChangeQuery class and queries against necessarily objects. For example, this trick might be used with custom timer job + SPChangeQuery queries to handle user permissions/groups or group changes as you have quite interesting stuff like GroupMembershipAdd/GroupMembershipDelete or RoleDefinitionAdd/RoleDefinitionDelete and so on in result sets.
SPRoleAssignment roleAssignment = new SPRoleAssignment(principal); SPRoleDefinition roleDefinition = web.RoleDefinitions.GetByType(roleType); roleAssignment.RoleDefinitionBindings.Add(roleDefinition); item.RoleAssignments.Add(roleAssignment); item.Update();