First off, the code has only been online for a day and I've already had a couple of people get in touch with suggestions, so thanks!
Another hard days working on the engine, I've fixed a few bugs, added a number of SpriteModifier's. Most noticably, I have began work on the particle engine.
The code is available right now in the unstable build section, and is due to be improved significantly. But as a proof of concept, I've taken a little video to show what's going on.
Unfortunately, I only have a crappy camera, and while it looks jerky I can assure you the demo averaged around 45fps, and looked significantly better in the flesh.
Take a look, and let me know what you think!