diff -u solr/project_solr.module solr/project_solr.module
--- solr/project_solr.module	18 Aug 2010 00:13:04 -0000
+++ solr/project_solr.module	18 Aug 2010 23:08:12 -0000
@@ -56,6 +56,11 @@
         'categories' => array(),
       ),
     ),
+    'project_solr_category_block' => array(
+      'arguments' => array(
+        'items' => array(),
+      ),
+    ),
   );
 }
 
@@ -408,7 +413,7 @@
     $variables[$delta] = project_block_render('project_solr', $delta);
   }
 
-  $search_path = 'project/' . drupal_strlower($project_type->name) . '/categories';
+  $search_path = 'project/' . drupal_strtolower($project_type->name) . '/categories';
   $variables['version_form'] = drupal_get_form('project_solr_version_form', $search_path);
 }
 
@@ -653,7 +658,7 @@
   apachesolr_current_query($query);
 
   // This hook allows modules to modify the query and params objects.
-  apachesolr_modify_query($query, $params, 'drupalorg_search_execute_base_query');
+  apachesolr_modify_query($query, $params, 'project_solr_view_category_block');
 
   $solr = apachesolr_get_solr();
   $response = $solr->search($query->get_query_basic(), $params['start'], $params['rows'], $params);
@@ -682,7 +687,27 @@
-      'content' => theme('item_list', $items),
+      'content' => theme('project_solr_category_block', $items),
     );
   }
   return array();
 }
 
 /**
+ * Render the final markup for the content of a category block.
+ *
+ * @param array $items
+ *   Array of links to projects in a given category block.
+ *
+ * @return
+ *   Formatted HTML markup for the category block content.
+ *
+ * @see project_solr_view_category_block()
+ * @see theme_item_list()
+ */
+function theme_project_solr_category_block($items = array()) {
+  $output = '';
+  if (!empty($items)) {
+    $output .= theme('item_list', $items);
+  }
+  return $output;
+}
+
+/**
@@ -710,7 +735,7 @@
     }
     if (!empty($terms)) {
       $terms = array('' => t('- Any -')) + $terms;
-      if (empty($label)) {
+      if (!isset($label)) {
         $label = t('Filter by compatibility');
       }
       return array(
@@ -1022,8 +1047,10 @@
  * 
  * @param string $path
  *   The base path to which the version form will redirect.
+ * @param string $label
+ *   An optional label for the form element.
  */
-function project_solr_version_form(&$form_state, $path) {
+function project_solr_version_form(&$form_state, $path, $label = NULL) {
   $query = apachesolr_current_query();
 
   $form = array(
@@ -1033,7 +1060,7 @@
   // Add version select field to our form.
   $version_alias = variable_get('project_solr_project_release_api_tids_alias', 'api_version');
 
-  $form[$version_alias] = project_solr_get_api_version_field($query, t('Select version'));
+  $form[$version_alias] = project_solr_get_api_version_field($query, $label);
 
   $form['path'] = array(
     '#type' => 'value',