Several components are functional, but all are still a bit in flux as the design matures.
Working well on one core. Designed to run one of these on each core. There's still some testing for the multi-core scenarios, but the GUI subsystem will be useful in creating test tools so priorities have switched there.
Gaffer and clients can create various event types and they are handled appropriately. Events moving from one process manager to another is implemented but not fully tested.
Fairly complete subsystem. Supports loading from zip files, allocating a user specified number of IO threads, and asynchronous IO calls from client processes where they don't have to worry at all about syncrhonization issues.
Basic functionality is there. Supports loading and rendering of actors in a scene. GUI support is in the process of integration.
Currently under heavy development. Will support skins and sizeable widgets. This subsystem is a high priority since building tools and demos of the engine's capabilities requires some minimal UI support.