This was just preemptive snubbing by Bush to the G-20.
I know people are annoyed by the lack of courtesy, but really, the rest of the world leaders are looking at Bush representing the country that just
made everybody else poorer -- or at least, that is how they will sell it to their constituents.
So basically, do YOU want a photo-op next to the guy who sent your VOTERS to the poor house?
Now you should read this as; World Leaders realize that things are about to get worse, and they do not want to be seen with the guy everyone is going