You may have noticed that ads for the Google Nexus One have been appearing all over my site... perhaps due to my fanboy-like coverage! Today I noticed a new version of the 728x90 unit that focuses on the Nexus One's navigational system. Notice that the ad includes directions that are relevant to my location (the Embarcadero in San Francisco). This could be the default image - but, knowing Google, I suspect that they feature directionally-relevant images for top DMAs (like San Francisco, New York, Los Angeles, etc):
