The way I would do this is to subscribe to the CellFormatting event of the GridView. Within the handler, you can check if the cell value is a date, check if it is 01/01/1900, and reformat accordingly:
this.radGridView1.CellFormatting += new Telerik.WinControls.UI.CellFormattingEventHandler(this.radGridView1_CellFormatting);