Ah, sorry, read it to fast. 

There isn't a property that on a per column level. 

We do offer it on the theme, which controls all columns: 

public class MyTheme : IGGridViewThemeDefinition
        {
            public override UITextAlignment HeaderCellTextAlignment {
                get {
                    return UITextAlignment.Center;
                }
            }
        }

gridView.Theme = new MyTheme();

Or you can override the dataSource and provide your own HeaderCell. Then you can set the cell's TextLabel's TextAlignment property.

public class MYDSH  : IGGridViewDataSourceHelper
        {
            public override IGGridViewHeaderCell CreateHeaderCell (IGGridView gridView, int column)
            {
                IGGridViewHeaderCell cell = (IGGridViewHeaderCell)gridView.DequeueReusableCell ("MYHEADERCELL");
                if (cell == null) {
                    cell = new IGGridViewHeaderCell ("MYHEADERCELL");
                    cell.TextLabel.TextAlignment = UITextAlignment.Center;
                }

                return cell;
            }
        }

-SteveZ

Yes. That was not the question though. How dow change the text alignment (Left, Right, Center)?