Who is just prefixing stuff for Webkit? Mixin libraries have been pretty standard for at least three years, and now Autoprefixer is starting to do the heavy lifting.
People only initially prefixed for Webkit because webkit was the only browser that had a lot of these properties. The problem was that nobody went back and updated their prefixes, which really only further illustrates one of the big problems with the whole idea of vendor prefixes.
> Vertical centering has been relatively easy since CSS 2.1 (Table model)
But not with divs which are more common
It's not hard, really: just use absolute centering [1]. That's actually what "margin: auto" is there for in CSS 2.1; it's a shame they were bad at evangelizing it.
…so you use table display rules on the divs?
The reason why many browsers rush to unprefix CSS3 is not that it's perfect, but because of the lazy web developers who only prefix stuff for WebKit. This may or may not bite the community in the future.