When I was a kid, yearbooks weren't a big thing until high school. I never got one in elementary school -- I only remember a few kids getting them, and they were just small paperback leaflets.
Nowadays, they're big hardback books like the ones I remember from high school, and it seems like pretty much all the kids get them. I didn't order one for my DS last year or the year before, but this year he told me that he felt really left out last year when everyone was passing them around to get signed. At first I stuck to my guns, insisting that he didn't need a yearbook, but then I realized I didn't really have a reason for not getting him one, other than that fact that I never got one when I was a kid (which seems like a really silly reason). So I ordered him one. I still think it's pretty frivolous, but I don't see the harm (except for thinking that, between him and DD, we'll have nearly 40 large hardbound books to store if we get them each one per school year).
Anyway, do you buy yearbooks at this age? In your region, is it the norm to buy yearbooks?