This may only apply to Australia, as I know little about the US education system, but...
There are a lot of really crappy teachers out there, who are useless and overpaid. This is a problem that has led to NSW giving government grants to any teacher who can prove themself not up to date, in order for them to leave the NSW education system. Yes, it's as backwards as it sounds.
There are also some very excellent teachers out there who do a great job and are very underpaid.
My course is excellent. I have no doubts than anyone who graduates my course is going to be an up to date, responsible teacher with the required skillset and a knowledge of the most recent educational developments. I also do not discount the skills of teachers who are experienced, but note the best ones are the ones who keep on professionally updating themselves with the latest research and methods.
Based on this, I think teachers need some accountability, but I also note that the education system is backwards and outdated, and needs serious reform, from the 3 r's (Reading, writing and Arithmatic) to a method based around the four r's as made up by some guy I can't remember to reference. (Recursion, Relation, Rigor, and I forgot the last one. I'll look the article up again sometime). Now, the good thing is that most progrssive schools are moving towards this sort of curriculum, as opposed to a discrete curriculum in which "english" and "maths" are entirely seperated and never cross paths. A more holistic method embracing outcomes and problem solving skills rather than remembering facts, that is.
For example, I *Like* open book tests because they're closer to real world conditions. I fully plan as a teacher to use open book tests whenever I can, and instead base the questions on actual understanding of the material, as opposed to memorisation. I also won't use multiple choice questions if I can help it.
Now, in light of this, I don't think testing is the way to prove teachers accountable, because teachers should be teaching skills that are difficult to test in any standardised way. The Queensland end of year thing is a good example, but I still find testing an inefficient process of measuring a teachers skills.
It sorts itself out naturally, in a way, since bad teachers end up getting jobs at worse schools, as better schools don't want them. The problem is these bad schools have the students that probably need better teachers far more to deal with the students there.
EDIT: Five minutes later, I look at one of my assigned readings which shows the sort of thing I'm talking about:
http://tiger.coe.missouri.edu/~jonassen/courses/CLE/index.html