The value returned from the UltraGrid.Selected.Rows property is of type SelectedRowsCollection; it contains references to each of the rows that are currently selected. You can pass this instance to the Clipboard.SetData method to put the rows on the clipboard.

You could also use the AllowMultiCellOperation property. Setting this to Copy will allow you to copy rows from the grid and paste them into the clipboard in a variety of formats like plain text and also certain Excel-compatible formats.