This hack prints the number of jobs at select cities from HN who-is-hiring pages.
The examples below show the 2 use cases in action.
(Notice the systematic increase in the number of jobs in Cambridge MA.)

bash-3.2$ ./city_distribution_in_HN_jobs.py http://news.ycombinator.com/item?id=2831646
52 jobs in Silicon Valley
23 jobs in New York
17 jobs in London
16 jobs in Cambridge MA
5 jobs in Chicago

bash-3.2$ ./city_distribution_in_HN_jobs.py 
##############################
August 2011
52 jobs in Silicon Valley
23 jobs in New York
17 jobs in London
16 jobs in Cambridge MA
5 jobs in Chicago
##############################
July 2011
75 jobs in Silicon Valley
27 jobs in New York
17 jobs in Cambridge MA
8 jobs in London
5 jobs in Chicago
##############################
June 2011
58 jobs in Silicon Valley
32 jobs in New York
15 jobs in London
13 jobs in Cambridge MA
5 jobs in Chicago
##############################
May 2011
67 jobs in Silicon Valley
14 jobs in New York
11 jobs in Cambridge MA
11 jobs in London
5 jobs in Chicago
##############################
April 2011
58 jobs in Silicon Valley
20 jobs in New York
11 jobs in London
6 jobs in Cambridge MA
6 jobs in Chicago


This python code depends on the HTML parser BeautifulSoup, available here:
http://www.crummy.com/software/BeautifulSoup/#Download