public class POITest {
  public static void main(String[] args) {
    //HSSFWorkbook exhibits correct behavior:
    Workbook workbook = new XSSFWorkbook(); 
    CellStyle vertTop = workbook.createCellStyle();
    vertTop.setVerticalAlignment(CellStyle.VERTICAL_TOP);
    CellStyle vertBottom = workbook.createCellStyle();
    vertBottom.setVerticalAlignment(CellStyle.VERTICAL_BOTTOM);
    Sheet sheet = workbook.createSheet("Sheet 1");
    Row row = sheet.createRow(0);
    Cell top = row.createCell(0);
    Cell bottom = row.createCell(1);
    top.setCellValue("Top");
    top.setCellStyle(vertTop); //comment this out to get all bottom-aligned cells
    bottom.setCellValue("Bottom");
    bottom.setCellStyle(vertBottom);
    row.setHeightInPoints(85.75f); //make it obvious
    try {
      FileOutputStream out = new FileOutputStream("test.xlsx");
      workbook.write(out);
      out.flush();
      out.close();
    } catch (IOException e) {
      e.printStackTrace(System.err);
    }
  }
}