Index: includes/cache.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/cache.inc,v
retrieving revision 1.48
diff -u -p -r1.48 cache.inc
--- includes/cache.inc	18 May 2010 18:26:30 -0000	1.48
+++ includes/cache.inc	28 Jun 2010 14:44:07 -0000
@@ -47,7 +47,15 @@ function _cache_get_object($bin) {
  *   The cache or FALSE on failure.
  */
 function cache_get($cid, $bin = 'cache') {
-  return _cache_get_object($bin)->get($cid);
+  // Check if the object exists in cache.
+  if ($cached = _cache_get_object($bin)->get($cid)) {
+  // Check if it is permanently cached (no expiry), or has not expired yet.
+    if ($cached->expire == CACHE_PERMANENT || $cached->expire > time()) {
+      return $cached;
+    }
+  }
+  // Either no cache object hit, or the returned object was expired.
+  return FALSE;
 }
 
 /**
Index: modules/simpletest/tests/cache.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/simpletest/tests/cache.test,v
retrieving revision 1.10
diff -u -p -r1.10 cache.test
--- modules/simpletest/tests/cache.test	13 Sep 2009 17:49:51 -0000	1.10
+++ modules/simpletest/tests/cache.test	28 Jun 2010 14:44:08 -0000
@@ -152,6 +152,21 @@ class CacheSavingCase extends CacheTestC
     $this->assertTrue(isset($cache->data) && $cache->data == $test_object, t('Object is saved and restored properly.'));
   }
 
+  /**
+   * Test that expired items are handled properly.
+   */
+  function testExpired() {
+    $test_string = 'Drupal rocks!';
+
+    // Set an item in the cache to expire in 10 seconds
+    cache_set('expired_test_string', $test_string, 'cache', time() + 10);
+    $this->assertCacheExists(t('Expired cache item found in cache'), $test_string, 'expired_test_string', 'cache');
+    sleep(20);
+    // Cache item should now be expired
+    $this->assertFalse(cache_get('expired_test_string'), t('Expired cache item not returned by cache'));
+  }
+
+
   /*
    * Check or a variable is stored and restored properly.
    **/