I happened across this very odd view of London on Google Maps....

Unlike the wonky view of San Francisco that resulted from the pasting together of multiple images, this seems as if it's had some kind of weird “etched in copper” Photoshop filter applied. Zooming up, you can guess some of the real reasons...

The shadows point almost due north, and are long, so it must have been taken in the heart of the winter. The bare trees along the riverbank also attest to that. The lack of trees certainly takes away some color, but I just don't get the overall muddy, copperish cast.

For comparison, here's the same close-up view via Yahoo! Maps....

In this case, Yahoo! Maps seems to look more reasonable.

Generally speaking, Google Maps still has better coverage than Yahoo! Maps, but I'm finding more and more cases where Yahoo! has better maps and/or better satellite coverage. As a case in point, I was looking around the other day at a friend's hometown (Puebla, Mexico), and found that Google Maps doesn't even mark Mexico City, one of the world's largest cities. For satellite coverage, they have some low resolution images where you can start to make out individual city blocks, but for the same area, Yahoo! Maps has fairly high resolution images where you can distinguish individual vehicles.