I think this is a more official way to do this:
UIDatePicker *datePicker = [[[UIDatePicker alloc] init] autorelease];
datePicker.datePickerMode = UIDatePickerModeDate;
[datePicker addTarget:self action:@selector(datePickerValueChanged:) forControlEvents:UIControlEventValueChanged];
datePicker.tag = indexPath.row;
textField.inputView = datePicker;