Facet block with dynamic title
You could change the block title in your theme or module using the theme function or theme preprocess function.

For example:

/**
 * Implements hook_preprocess_facetapi_title
 */
function HOOK_preprocess_facetapi_title(&amp;$variables) {
  $some_condition = TRUE;
  // If some condition
  if ($some_condition) {
    // Some title..
    $title = t('Custom title');
    // Set theme/template variable for title
    $variables['title'] = $title;
  }
}


See also: theme_facetapi_title