I address this further down thread, but in a nutshell: there are effective, fair ways of evaluating teacher performance [1]. And I'm all for them. Standardized test performance is not on of those ways. Furthermore, in a lot of the schemes currently being put into place, teachers are not evaluated by test scores at the school level, but at the district or state level. Teacher evaluation is necessary, but it's not easy. Trying to shortcut things by asking standardized test score to do more than they are capable of (which is not much) is exactly the kind of thing that drives good people out of teaching.

[1] See: http://www.epi.org/publication/bp278/ and http://www.washingtonpost.com/blogs/answer-sheet/post/meet-a...