I noticed this recently. I have been playing Skyrim and noticed for the last couple of days that the lip sync is working like before.

According to this thread it has apparently never been fixed: http://www.gamesas.com/topic/1502140-regarding-the-lip-sync-bug-6/

There hasn't been an official bug-fix patch for Skyrim in a long time, so no, it hasn't been fixed.

And let's use that thread linked above as it has all the info on attempts to fix it.