You would be correct. Archlinux has had 3.6 for a while (i don't use it, since i use a custom-kernel, but i do remember when it first came through as an update and obviously there have been subsequent point releases since then.). ..and yeah, I know for myself anyway, on a fresh Arch install i usually only install the bare minimum to have a working system (ie: base-system + pacman and that is it)... Then reboot and update, then start installing DE, common apps, etc.
they don't handle it. There is no out-of-the-box support and zfs is a 'tech-preview';
it's still cool that you can use ZFS (if that flips your boat). But then again, this isn't some amazing feature that only they (or gentoo) offers. If you want zfs in Archlinux, you can do that very easily too;
https://wiki.archlinux.org/index.php/ZFS &
https://aur.archlinux.org/packages/?O=0&K=zfs ... it looks pretty simple to install/use, as well ~ just a few commands (install zfs + kernel/modules), and some additional work if using zfs for your root partition (simple, still).