Is it a coincidence? The last time I recall an airship over Canberra (advertising some obscure brand of chocolate) was when the US President was in town. In fact I vaguely recall it arriving in an enormous aircraft before being let loose (we are near the airport).
Now, with APEC bringing Dubya to Oz, I see the Holden airship buzzing around. I wonder if it is on its way to Sydney to watch out for snipers?