Common subdirectories: views_bulk_operations_old/translations and views_bulk_operations/translations
diff -upN views_bulk_operations_old/views_bulk_operations.js views_bulk_operations/views_bulk_operations.js
--- views_bulk_operations_old/views_bulk_operations.js	2009-04-07 12:42:22.000000000 -0700
+++ views_bulk_operations/views_bulk_operations.js	2010-08-22 06:39:31.003429418 -0700
@@ -51,6 +51,7 @@ Drupal.vbo.selectAll = function() {
 }
 
 Drupal.vbo.startUp = function(context) {
+
   // Reset the form action that Views Ajax might destroy.
   $('form[id^=views-bulk-operations-form]').each(function() {
     $(this).attr('action', Drupal.settings.vbo.url);
@@ -89,3 +90,16 @@ Drupal.behaviors.vbo = function(context)
 // END jQuery
 })(jQuery);
 
+var vbo_only_one_checkbox = function () {
+  // pached by Vadim
+  $("input[name^=objects]:checkbox").each(function() {
+	var checkbox_name = $(this).attr('name');
+	$(this).bind('click', function() {
+	  $("input[name^=objects]:checkbox").each(function() {
+		if ($(this).attr('name') != checkbox_name) {
+		  $(this).attr('checked', false);
+		}
+	  });
+	});
+  });
+}
\ No newline at end of file
diff -upN views_bulk_operations_old/views_bulk_operations.module views_bulk_operations/views_bulk_operations.module
--- views_bulk_operations_old/views_bulk_operations.module	2010-02-03 16:43:02.000000000 -0800
+++ views_bulk_operations/views_bulk_operations.module	2010-08-22 06:38:25.835285221 -0700
@@ -170,6 +170,10 @@ function theme_views_node_selector($elem
       );
       array_unshift($rows, $row);
     }
+	// Limit for selection of only one checkbox
+	if ($view->display['default']->display_options['style_options']['limit_to_one']) {
+	  drupal_add_js('(function ($) { vbo_only_one_checkbox(); })(jQuery);', 'inline', 'footer'); 
+	}
 
     $output .= theme('table', $headers, $rows, array('class' => $vars['class']), $title);
     $output .= theme('hidden', $element['select_all']);
@@ -398,6 +402,13 @@ function views_bulk_operations_form_alte
  * @see views_bulk_operations_form()
  */
 function views_bulk_operations_form_validate($form, &$form_state) {
+
+  // if configured single option have to be selected
+  if ($form_state['values']['plugin']->view->display['default']->display_options['style_options']['limit_to_one']) {
+	if (count(array_filter($form_state['values']['objects']['selection'])) > 1) { 
+	  form_set_error('objects', t('Two or more options have been selected. Please select single option.'));
+	}
+  }
   switch ($form_state['values']['step']) {
     case VIEWS_BULK_OPS_STEP_VIEW:
       $_SESSION['vbo_values'][$_GET['q']] = $form_state['values'];
diff -upN views_bulk_operations_old/views_bulk_operations_plugin_style.inc views_bulk_operations/views_bulk_operations_plugin_style.inc
--- views_bulk_operations_old/views_bulk_operations_plugin_style.inc	2010-02-03 16:43:02.000000000 -0800
+++ views_bulk_operations/views_bulk_operations_plugin_style.inc	2010-08-22 06:00:55.275452020 -0700
@@ -11,6 +11,7 @@ class views_bulk_operations_plugin_style
     $options['display_result'] = TRUE;
     $options['merge_single_action'] = TRUE;
     $options['hide_select_all'] = FALSE;
+	$options['limit_to_one'] = FALSE;
     $this->populate_operations($options);
 
     // Per-action settings.
@@ -46,6 +47,12 @@ class views_bulk_operations_plugin_style
         t('Each action as a separate button'),
       ),
     );
+    $form['limit_to_one'] = array(
+      '#type' => 'checkbox',
+      '#title' => t('Limit for selection of only one checkbox'),
+      '#description' => t('Check this box to limit selection of checkboxes to one in the same time.'),
+      '#default_value' => $this->options['limit_to_one'],
+    );
     $form['hide_select_all'] = array(
       '#type' => 'checkbox',
       '#title' => t('Hide select all checkbox'),