I'd love to see up to date stable grsecurity kernel repositories for the major distributions (ubuntu, debian, rhel/centos) that provide patched versions of the distribution kernel. You can configure most of grsecurity via the sysctl interface. At the moment it is always a bit of hassle to patch & compile a kernel from hand even with the great debian/ubuntu kernel-package.
I don't think I'll use an extra distribution. But something like a hardened LAMP/LAPP stack for shared hosting out of the box in a distribution would be great (I think in terms of easy chrooting of users and php, secure permissions, etc.pp) However, I guess everyone has different needs and there is no one size that fits for all.
I don't know. I'm just on the end-user side. Just a guess from my (pretty limited) understanding of the issue: The grsecurity[1] patch includes PaX[2] that can break a lot of software. e.g. Java and X11 and there are sometimes other unwanted side effects as well. And I've found a blog post stating that the author does not want to maintain a upstream patch[3].