Earlier this month the L.A. Times stated they will release ratings for 6,000 teachers based on a value-added measure of teacher performance using student standardized test scores (http://articles.latimes.com/2010/aug/15/local/la-me-teachers-value-about-20100815).
The Economic Policy Institute has released a briefing paper regarding the problems with using student test scores to evaluate teachers: http://epi.3cdn.net/724cd9a1eb91c40ff0_hwm6iij90.pdf. What do you think?