Chris has written an interesting post about how one of her readers figured out her exact address. (well, okay it doesn't tell you HOW she did it, but that she was able to.) The pertinent parts of the story are in the last couple paragraphs, and the comments give more information too.
Sigh. What a world! Although I'm glad to know that I'm not totally crazy when I do smudge cities & other information in online photos.