I saw this article both on the New York Times website and then on Prof. Larsen's blog. With Kim Jong Il's pictures disappearing, speculations abound. This particular article deals with Japanese perceptions of this. Acting secretary general of the Japanese Liberal Democratic Party Shinzo Abe senses that a regime change in North Korea is imminent.
One high-ranking North Korean defector mentioned, however, that Kim himself gave an order to remove pictures of him from one building years ago, but no one had the nerve to do it.
One Korean News Service official denies anything unusual about the removal of the portraits, writing it off as solely routine updating and cleaning. This makes sense to me, that they would want an updated picture of Dear Leader. It would seem strange to me if they now said it was just for cleaning and some kind of military coup develops. It would make them seem like liars to the people. (Not like they're not already lying.) Only time will tell, but I don't anticipate any significant power shift soon.