Sorting in datagrid in Silverlight for custom columns - SortMemberPath

SortMemberPath :

Sometimes the property that your column is bound to is not always the one that you want it to sort by.
SortMemberPath is on DataGridColumn, you can use this beyond just template columns and can actually have a column bound to one property, but sort based on another property.

<data:datagridtemplatecolumn header="Start Date" width="110" sortmemberpath="RoomEffectiveOn"></data:datagridtemplatecolumn>