Teacher performance is a hot issue throughout formal education. Washington DC's superintendent, who instituted a new evaluation system (which seems intended to better reflect actual work performance) recently canned 241 teachers who received the lowest ratings (indicating unsatisfactory job performance). That's over 2.5 times more than were let go last year. Tamar Lewin recently filed a report on the situation: http://www.nytimes.com/2010/07/24/education/24teachers.html?hpw
The issue is also being addressed at the university level. According to University Affairs, the Faculty Senate at the University of British Columbia, which sets educational policy, had voted to actively use student evaluations of teaching in making personnel decisions, like promotion and tenure. The faculty association (union) challenged it, saying that it violated the union contract, and took the university to court. An appeals judge sided with the Senate. Léo Charbonneau's report primarily focuses on the legal issues involved, but the personnel issues are no less compelling. Check out the report at http://www.universityaffairs.ca/senate-decision-vs-bog.aspx.