Some homeschoolers on this board have done the MAP testing through their local public schools. Dazey used a company out of Florida. Here's a link to the thread:
http://giftedissues.davidsongifted....8214/those_who_tested_w_NWEA_MAP_th.html

I think most districts are giving all the kids the test because it can help predict the NCLB results. The big issue is what they do with the MAP results. I've started to notice a shift in my district in the language. It used to be the stated goal was every child reaches proficiency. Now, the latest message from the superintendent is "every student makes at least a year�s growth each school year and that those who are behind grow even more so that we can close the gaps."

DD8 started at an accelerated cluster magnet and I was impressed they looked at what % of students were achieving at the 95% on the MAP test. If a school has a goal to make sure each child achieves a year's worth of growth, it's harder to ignore the needs of the gifted. This is one of the reasons I think the MAP test helps advocacy efforts for the parents of gifted children.