Euan Semple posted about the division between 'the have' and 'the have not' in New York. It is similar to my experience of San Francisco. That a divide exists is unsurprising but I was totally unprepared for how sharp the divide is.
Interestingly there was also a link provided to Gap Minder and to Hans Rosling blog in the comments. Both are worth looking at, and contain a wealth of interesting ideas and information on human development.