It really depends upon the school, from what I've seen. Some are much more mainstream than others. I'vehad a similar concern, because my family is such a group of technocrats. DD decided on her own that she wanted to start learning to read, so i've supported it in some small ways. My school doesn't seem as extreme as some of the stories i've heard here. I see kids wearing shirts with logos. When i mentioned a trip to Disney world, a teacher's response was "how fun!" When I asked a teacher about my 18 month old's obsession with numbers and letters, i actually got some good advice about how to support it without pushing it.
All that to say, I think it will depend upon your school. We've had a very open and accepting experience so far.