Math Mammoth Grade 1 Complete Curriculum is now aligned to the Common Core Standards.
Here is a document listing the lessons and the corresponding standards.
I will record here the main changes in its content as compared to the earlier edition / version (through April 2012).
You can tell the new edition and the earlier ones apart by their cover image: the edition aligned to the Common Core Standards has these new cover images.
What used to be chapter 4 (Place Value) switched places with Chapter 3 (Addition and Subtraction Facts within 0-18).
The topics of rounding, even & odd numbers, and parenthesis were taken off as they are not in the Common Core standards for grade 1.
There are many new lessons about adding and subtracting within 20, and adding and subtracting two-digit numbers without regrouping, explaining basic mental math principles.
The lesson "Exploring Measuring" is split into two lessons (Measuring Length and Exploring Measuring). Both lessons are expanded from what they were before.
Geometry section was expanded and changed. It now has more material about shapes.