MAP stands for Measure of Academic Process, so to me it is just a way for schools to see who is making progress, how much progress is being made, and who might not be making as much progress as they should be. Our school district doesn't get permission from parents to use this testing instrument, but they do put the dates on the school calendar so parents know when they are testing. We also don't get the results of the testing unless we ask for it because our school just uses the results for AR placement and to catch any students that are struggling. I don't know of any students that have been accelerated because of their MAP scores.
I know a lot of parents on this forum put a lot into MAP testing, but I don't view it the same way - especially the reading test. Sure it is a great way to help our DC prove they should be able to check out higher level books at the library, but after a child has sat through this test a few times it is very easy for them to stop trying so hard. The test basically keeps going and gets harder as the student answers the questions until they miss so many at a certain level then they are done. These kids are smart (well duh!) and they figure out that if they just buzz through this test they can be done and then do something more fun (like read or get on a computer game) while the other students finish their test.
For my DD - once she has proven she can do something she has a hard time repeatedly proving it just because the teacher wants her to and that is the case with the MAP test. It was fun when she took it at the end of 1st grade to prove to the school she was advanced (she scored at about a 4th grade level if I recall correctly), but what did she get out of trying hard and proving herself - not much and more of the same! Now she has taken the same test several times each year since then and she just doesn't see the point. She is still scoring at least 2 grade levels above and the school library will let her check out any book she likes - big whoop-ti-do! I'm sure if I told her something would be different/better for her if she could score really well, then she would try, but for us it makes no difference if she scores at or above level.