On Linux distributions, however, you either have to wait for the next distro release (whether that be 4 months or 12 months) or use hackish solutions only a Gentoo user could love. Of course, I could just use OS X (or Windows) but that's not the point - I like the tweakability/freedom of Linux, but I just want to be able to update, for instance, my kernel or ACPI packages separate from my glibc and Xorg without leaving the realm of the package system.
In any case, this is probably best reserved for the -devel list, as it has gone outside the scope of my main question (how to make backports) and into the realm of release cycles etc.