Now I stumbled upon a new, English one:
It doesn’t only show the public transportation but also restaurants, banks, cinemas, theaters, … Here an example of the area around Nanjing Lu:
But the most beautiful maps of Shanghai come from edushi (E都市, E-City):
They have already covered many Chinese Cities and seem to want more.
So why Yahoo, why, why, why don’t you make maps, buy maps or allow the use of one of the above mentioned ones in flickr?