[filburt1]

Update: if you have PAPI 1.0.5, find:

else if (thisis("newthread") && actionis("postthread"))
{
    updatethreadtitlecache(false, $_POST['forumid'], $_POST['subject']);
}

After it, add:

else if (thisis("newreply") && actionis("postreply"))
{
    updatethreadtitlecache(false, $_POST['threadid']);
}

That will force the last post title to update after a reply to a thread.

Also an important note: for you to be able to cron the update all script, this mod must be in the default style set.