SourceForge recently changed their site to put their Apache servers behind a "pool" of Nginx reverse proxies (accelerators). This is a good idea, but has negative impact on various Drupal features, like, logs, ACLs etc. I've made a small hack on my http://pysearch.sourceforg.net/ Drupal installation, like this:

--- includes/bootstrap.inc.5.10 2008-09-23 08:53:05.000000000 -0600
+++ includes/bootstrap.inc      2008-09-20 10:14:52.000000000 -0600
@@ -5,6 +5,9 @@
  * @file
  * Functions that need to be loaded on every Drupal request.
  */
+if ($_SERVER['HTTP_X_REMOTE_ADDR']) {
+    $_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_X_REMOTE_ADDR'];
+}
 
 /**
  * Indicates that the item should never be removed unless explicitly told to

Granted, this needs to be configurable, I'm thinking a general Drupal setting where we can tell which Header to use to replace REMOTE_ADDR.