It is a Common Lisp OS development platform.

From its home page (see below):


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, embedded, and single-purpose applications. There can potentially be several completely different operating systems built using Movitz.