Cleese is a project to build a functioning operating system written almost entirely in Python. The basic idea is to have a microkernel mostly based on the Python VM and all other operating system functionality written in Python. James Tauber and Dave Long successfully built a proof-of-concept back in 2003. You can see that work, along with some historical information at: http://code.google.com/p/cleese/ This is a reboot of the project, starting largely from scratch. James Tauber is now joined by Brian Rosner. To get started, see BUILDING_TOOLCHAIN and SETTING_UP_DISKS.