The latest "news" is that Frazer Hines said at London Film and Comic Con that someone unspecified had called him a few weeks ago saying that everything except "The Highlanders" had been found. Hines was excited at the time, but hasn't heard anything else and no longer believes it. On the other hand, an employee at Who Shop in London told another poster that he "knew for a fact" that episode 2 of "The Highlanders" had been found. Also, someone apparently started to ask a question about missing episodes at a Doctor Who event at London Film and Comic Con, but was cut off by the moderator.
...Another day, another encapsulation of what missing episode rumors and gossip are worth.