Some states want to get all their students to take Algebra by the end of grade 8. The idea is that this will provide equal access to challenging curricula.
The Washington Post's Jay Matthews discusses the issue in Recalculating The 8th-Grade Algebra Rush and the original report is available here: The Misplaced Math Student: Lost in Eighth-Grade Algebra
I'm a fan of Algebra and a fan of helping as many students as possible master it, but I am not a fan of aggressive time lines for when it has to get done. Pushing all 8th or even 9th graders into Algebra is a problem. Kids who are not ready for Algebra would be better served by shoring up their math foundations. They need better arithmetic skills and they need better number sense. Students who are pushed into Algebra before they are ready are doomed to fail and are probably doomed to hate math forever. I don't want them to take silly math classes that lack any rigor, but I don't want to throw them into classes for which they are not prepared.
At the other end of the spectrum, there is also a push to get good math students to take Algebra in seventh grade or even earlier. Not every kid is ready for Algebra in eighth grade. Very, very few kids should be taking Algebra before eighth grade. If a kid is that good at math, why not provide a more rich mathematical curriculum for the kid instead of just having them rip through the same old courses more quickly?