Currently, RadListView does not support typed columns but it should sort the values according to their types and without taking them as strings. This might depend on the way you populate your list view with data. Your DateTime values might somehow get cast to string while populating the list view. The following code sample demonstrates how to add values to RadListView in order to be able to sort according to the DateTime values:
this.radListView1.Items.Add("asdf" + i, DateTime.Now.AddHours(i), "col 3", DateTime.Now.AddDays(i));
I hope this will help you. If you continue experiencing difficulties, please send me a code snippet which demonstrates the way you setup the RadListView. This will help me provide you with a proper solution.