It's been there since the image of the TIME magazine cover of the archbishop went up on his homepage. Follow the link to the homepage above and hover your mouse over the image. Or, if that doesn't work for you, follow this link to a static popup image of the homepage.
The subliminal message? It could be that the Archbishop of Canterbury is cross with his flock. Or it could be that his homepage needs some sprucing up and updating; notice that if you follow the link titled "Archbishop Williams and current events" you get information from events in 2004, 2003, and 2002 but nothing more recent.
And is anyone else bothered by the way the left margin on some of the pages follows you as scroll down? I find it a distracting gadget. Here's an example:
Click and scroll to see the dizzying effect.