Both LINQ to SQL and the ADO.NET Entity Framework provide change tracking when entity objects obtained from the database remain 'connected' to the DataContext or ObjectContext object through which they were retrieved. However, when the entity objects are disconnected this automatic change tracking is lost. People are busy trying to come up with their own way of tracking changes to the data in the objects so that the database can be updated efficiently and correctly.
I find it highly surprising that neither of these technologies provides a 'disconnected' capability especially considering that
a) disconnected scenarios are common
b) such a capability has previously been provided through datasets.