Hi Christoph,
Currently this feature is not possible in GridDataBoundGrid. But you can use the virtual events to swap the roles of the rows and columns. Please refer to the following KB article discusses about the steps to transpose the rows into columns and vice versa using the Virtual Grid.
http://www.syncfusion.com/support/kb/grid/Default.aspx?ToDo=view&questId=315Best regards,
Haneef