I would describe DD's current school math situation as homework differentiation, rather than in-class differentiation, but that may be changing in the future.
DD was begging for more advanced math in 1st grade, and mid-year her teacher said she would try to give her "bigger numbers" to work with, but her teacher never got around to it, and never actually did a single thing to differentiate or accelerate her math instruction. Very frustrating! I ended up buying her some "gifted" math workbooks from Prufrock.com for her to use at home, and when DD found multiplication and division flash cards in the Target dollar bins, I agreed to buy them for her.
I met with the principal and a 2nd grade teacher at the end of 1st grade to ask what they could do for her in 2nd grade. They were hoping to start a small advanced pull-out math class for 2nd and 3rd graders, but hasn't happened. The teacher started giving her more advanced math homework within the first few weeks of school, usually on the topic the class is covering. They use Investigations, which is spiraling. She started with 3rd grade worksheets, then 4th grade, and now her math homework tends to be variety of stuff from math-drills.com.
There hasn't been any differentiated math instruction during the school day, but the teacher has said that she is willing to meet with DD at the end of the day if she has any questions about her homework. Mostly I just answer her questions as they come up, with occasional elaboration/instruction as needed. During math time at school, DD participates with the class, and does the worksheets they do in class. I think this is mainly due to the fact that the class takes required math assessments together, so the teacher wants her to be exposed to the material before the tests. DD and 2 of her classmates miss one math period each week due to a pull-out in a different subject, but at least she isn't required to make up what she missed.
The school also uses the First In Math website, so DD can work ahead at her own pace at home this year, and the teacher can see how she's doing. That site is more for practice than instruction, but DD is enjoying it since she can choose to practice topics they haven't covered in class. When she is untimed, she has aced the 5th grade stuff she tried. In the timed section, she is about 2/3 of the way through the 4th grade skill set. Another benefit to the website is that she can click or type much faster than she can write as a 7-year-old.
Last week DD's teacher surprised me by asking if I had any suggestions for math books or additional websites she could use with DD. Based on posts I read here, I recommended the Challenge Math books. The teacher had a positive reaction. I look forward to seeing how that goes.
DD joined a weekly afterschool math class for kids at a local university, but it is a idea-discussion group, not a skill-drill class. For example, one day, in a discussion about doubling numbers, they learned about finger binary counting, and made a big chart showing how many combinations they could think of with the fingers of one hand held up or down. Then by adding fingers, they could keep counting higher and higher. This class is really fun for her, and now her math-thinking time isn't limited to working alone on the computer or just with me.
The school did start a split 4/5 advanced math class this year, and I'm going to ask if DD can go to it in 3rd, assuming she doesn't do a full grade acceleration. I know she could handle it this year, but the 2nd grade schedule is not in sync with the other grades. Since she is already pulled out 3 times per week, I think her schedule would be a mess.