I will have more to say about this at some point, but for now I thought you might just be interested in seeing the 2008 MEAP and MME results for the county. [These links are from the WISD, and I'm not sure why charter schools are not listed.] No surprise that the results mostly track closely to numbers that assess poverty, like free and reduced price lunch.
1. Background information on what was assessed. Note that you will also find the links to past years right there.
2. 2008 MEAP results
3. 2008 MME results
Although the results came out a few weeks ago, I couldn't find them on the AAPS web site (there is, however, a detailed analysis of 2005-2006). Nor could I find them on the Saline Schools web site. The Ypsilanti schools web site links directly to the state (and that is a good solution, I think, because the state updates the data every year and so it is immediately available). I stopped looking when it became clear a lot of school systems have not updated their web sites (yet).
Or you can go to greatschools.net, here is the Michigan MEAP link. (And at greatschools.net you can also look up information about the free lunch program, race/ethnicity, student/teacher ration, and more.)