diff -u solr/project_solr.module solr/project_solr.module
--- solr/project_solr.module	19 Aug 2010 01:31:44 -0000
+++ solr/project_solr.module	19 Aug 2010 02:28:00 -0000
@@ -773,36 +773,39 @@
 //----------------------------------------
 
 /**
- * Build a Solr query to find project nodes.
+ * Build and execute a Solr query to find project nodes.
  *
- * @param object $project_type
- *   A taxonomy term object for the project type to query for. Must include at
- *   least 'tid' and 'name' fields.
+ * @param string $base_path
+ *   The base path to use for the Solr query.
  * @param array $filters
  *   Optional array of Solr filters to add to the query.
  *
  * @return
  *   An ApacheSolr $query object. // TODO
  */
-function project_solr_build_project_query($project_type, $filters = array()) {
-  // Build a simple query.
-  $base_path = 'project/' . drupal_strtolower($project_type->name);
-  
-  $filters = isset($_GET['filters']) ? $_GET['filters'] : '';
-  $query = apachesolr_drupal_query('', $filters, '', $base_path);  
+function project_solr_run_project_query($base_path, $filters = array()) {
+  $filterstring = isset($_GET['filters']) ? $_GET['filters'] : '';
+  $query = apachesolr_drupal_query('', $filtersstring, '', $base_path);  
+
+  // Figure out all the fields we need to use as facets.
+  // First handle all the implicit filters we're going to add ourselves.
+  $facet_fields = array(
+    'type',
+    'im_project_release_api_tids',
+  );
+  // Now add any fields used for optional filters from our caller.
+  if (!empty($filters)) {
+    foreach ($filters as $filter) {
+      $facet_fields[] = $filter['key'];
+    }
+  }
 
   $params = array(
     // The fields to return.
     'fl' => 'id,nid,title',
     'start' => 0,
     'rows' => 5,  // TODO: make this configurable.
-    // We need to be able to facet on the project vid value
-    // so we can pull project categories.
-    'facet.field' => array(
-      'type',
-      'im_vid_' . _project_get_vid(),
-      'im_project_release_api_tids',
-    ),
+    'facet.field' => $facet_fields,
     // Filters are set below via explicit calls to add_filter() rather than 
     // here in the $params array. This is because any filters passed to 
     // apachesolr_drupal_query() will override filters set via the $params
@@ -820,7 +823,7 @@
   // This can e.g. be used to add available sorts.
   foreach (module_implements('apachesolr_prepare_query') as $module) {
     $function_name = $module . '_apachesolr_prepare_query';
-    $function_name($query, $params, 'project_solr_view_category_block');
+    $function_name($query, $params, 'project_solr_build_project_query');
   }
 
   // We add our fields after the prepare_query() because prepare_query()
@@ -830,7 +833,6 @@
   // category. These values are not passed in the url, so we add them here
   // ourselves to ensure we only get the content we want.
   $query->add_filter('type', 'project_project');
-  $query->add_filter('im_vid_' . _project_get_vid(), $project_type->tid);
 
   if (!empty($filters)) {
     foreach ($filters as $filter) {
@@ -838,6 +840,19 @@
     }
   }
 
+  // Cache the built query. Since all the built queries go through
+  // this process, all the hook_invocations will happen later.
+  apachesolr_current_query($query);
+
+  // This hook allows modules to modify the query and params objects.
+  apachesolr_modify_query($query, $params, 'project_solr_view_category_block');
+
+  $solr = apachesolr_get_solr();
+  $response = $solr->search($query->get_query_basic(), $params['start'], $params['rows'], $params);
+
+  apachesolr_static_response_cache($response);
+  apachesolr_has_searched(TRUE);
+
   return $query;
 }
 
@@ -1090,27 +1105,15 @@
 function project_solr_fetch_category_items($project_type, $category_term) {
   $filters = array();
   $filters[] = array(
-    'key' => 'im_vid_' . _project_get_vid(),
+    'key' => 'tid',
     'value' => $category_term->tid,
   );
-  $query = project_solr_build_project_query($project_type, $filters);
+  $base_path = 'project/' . drupal_strtolower($project_type->name);
+  $query = project_solr_run_project_query($base_path, $filters);
 
-  // Before we call modify_query() we want to save the URL query values so
-  // that our 'More' links are cleaner and free of excess junk.
   $query_values = $query->get_url_queryvalues();
 
-  // Cache the built query. Since all the built queries go through
-  // this process, all the hook_invocations will happen later.
-  apachesolr_current_query($query);
-
-  // This hook allows modules to modify the query and params objects.
-  apachesolr_modify_query($query, $params, 'project_solr_view_category_block');
-
-  $solr = apachesolr_get_solr();
-  $response = $solr->search($query->get_query_basic(), $params['start'], $params['rows'], $params);
-
-  apachesolr_static_response_cache($response);
-  apachesolr_has_searched(TRUE);
+  $response = apachesolr_static_response_cache();
 
   $items = array();
   if ($response->response->numFound > 0) {
@@ -1126,6 +1129,7 @@
       'class' => 'more',
     );
   }
+
   return $items;
 }