The Agency: The Body at the Tower is published in the UK by Walker Books. It looks like this:
In France, it will be published in February 2011 by Nathan Jeunesse as Le meurtre de l’horloge:
The Spanish edition, published by Ediciones Versatil, is called Los Crimenes del Big Ben:
Here’s the Italian cover for La Detective. Passeggiata nel vuoto, published by Mondadori.

I’ll post more international covers as they come my way!