Frode Vatvedt Fjeld has been writing a program that boots an x86 computer directly into a Lisp environment. From his description:
The Movitz system aspires to be an implementation of ANSI Common Lisp that targets the ubiquitous x86 PC architecture "on the metal". That is, running without any operating system or other form of software environment. Movitz is a development platform for operating system kernels, and potentially there can be several completely different operating systems built using Movitz.
He's been discussing it on #lisp for the past few weeks, and I recently tried it out with bochs:
Should be interesting to see where it leads.