Columbia's MPH actually can be done in a year in the General Public Health track. It is open only to those with doctoral degrees or significant health experience. Rather than applying to a department, one applies to the GPH track. All of the courses are electives, except for the core courses required at all schools of public health. Although the program can be completed in a year, the number of credits required are the same as for 2-year students, so it's a great deal of work - around 7-8 courses per semester. Some Columbia medical students do the program between their 3rd and 4th years. I was accepted to the program and almost attended, but Hopkins better met my needs for a number of reasons, including the fact that the Hopkins MPH is an 11 month program running from June through the following May, so it synchronizes perfectly with the medical year (July-June).
I know that there were a couple of participants on this board last year who joined the Columbia GPH track, and maybe they can comment on their experiences, it they are still reading these discussions.
Here is the General Public Health link:
http://www.mailman.hs.columbia.edu/...uction/general-overview/general-public-health