There is an init system written in Tcl included in EtTcl.
aspect 2014-01-15: rkeene has also done interesting work in the direction of an init system, parts (all?) of which can be found in TUAPI and in action in the AppFS and AppBox projects, which I'm sure he'll elaborate on in due course. Here are some choice quotes from the chat to motivate interest:
(rkeene on the chat, 2013-08): AppBox is an appliance for running server apps, once you get past the initrd there's a lot of other stuff (glibc is part of the Core package) -- it's a lot like Android, but with more common things. The "system" module is just part of the admin tclkit (statically linked) in the initrd (which consists of /tclkit, /init -- a tclkit script, and /dev/console).
(rkeene on the chat, 2013-11): (AppFS is) a FUSE-based filesystem for running software from the Internet without installing it by using a global namespace and aggressive cache. Most of the FUSE just talks to Tcl to do the work. My userspace has 4 files: /init (which is a Tcl script); /bin/tclkit (TclKit); /bin/appfsd; and /dev/console. You can boot without ld.so. It's a static tclkit with my TUAPI extension, for things like modprobe, ifconfig, brctl, vconfig, etc.