Currently, there is one user for testing: exampleuser, with password 123; logging in as a guest also works. There's only one app, and a basic UI, but this is probably enough to work with if you want to make your own distro! If you enable the debug mode [set debug_level to 3], there'll be a terminal; space to insert commands.
Changes since build 1000: There is now an example app! The Message Queue api now works well enough to support apps. Documentation is in "kernel//wmqengine". Server-side decorations work - no need to make your own buttons!