I think it is really dependent on the Montessori school. DD3 is in a Montessori school that was recommended by our psych (who specializes in GT kids) and although we are moving her to same school at DS (we knew it would only be for 1-2 years max since hers only goes to around the eq of first or second grade).
We have visited and heard of wide range of Montessori schools - some where I can completely see where the school would have no clue about giftedness.
In DD's case (she is in the class with 3-5 year olds), since the classes are mixed age, I don't see a lot of comparisons to what a typical age peer would be like I did in the previous preschool at our PT conferences. She gets to hang out with older and younger kids.
In her classroom, they do really allow them to go at their own pace - her teacher told us that sometimes DD would sometimes sit with her activity close to a lesson for the older kids and although appear not to be listening, as soon as the lesson was over, she would get it out and do it correctly, and they don't force her to put it back. She has been showing a lot of interest in some areas so they have been encouraging her and they are aware of her ability to pick up things quickly.
I would imagine - in a good Montessori school, where they do really follow the child's pace, there should not need to be identification for GT specifically but rather work seamlessly so if the child needs materials from next class, they could get those materials. However, Montessori name is used and misused frequently so it would really be dependent on school, like any other school.
Montessori as a concept and the implementation of those same concepts are two totally different things.
