Here are my thoughts: Although I am very disappointed with the list, I do not take it seriously. I have no regrets in my choice of fields. I am learning analytical and leadership skills in my graduate program. Not everyone can become a scientist or physician assistant. Payscale figures are also not credible because it doesn't take into account a person's practice area. Social work and library science are very diverse fields; the practice area can lead to different salary levels. The list is also discriminatory because women disproportionately attain most of the "worst degrees."
The bottom line is focus on what interests you, excel in the subject, and your career will take off from there. Don't listen to dubious rankings that adopt arbitrary data. I love this comment because it reveals why society needs librarians:
Forbes should have asked someone with a Master's degree in Library & Information Science about the difference between nurses and PAs. This is what happens when information professionals are devalued in our society.
[UPDATE] In 2012, Forbes revisited this list with their ranking of best and worst master's degrees for jobs. It removed social work from the list (woo-hoo!), but library and information science still remains on the list for worst master's degrees.