It uses SDL instead of Allegro, Allegro stuffs have been completely removed.
Currently saving and restoring game works, as well as networking (I've just fixed it).
There are still texturing bugs on several systems but yet on those same systems 0.6 didn't even run last week

Currently you can script units using the COB Virtual Machine and soon Lua scripts, game scripts are written in Lua and AI can be scripted with Lua too. There is also a global Lua interface to allow Lua scripts (AI, game script, units, ...) to share information.
All scripts run in a thread based model, every Lua thread (or coroutine) that is started from the engine can be run as a real thread (and all its sub threads too if it's the main Lua thread). This will allow real parallelism for AI or using different priorities for several mission objective checks in campaign mode.
So what's working currently:
_ single player skirmish mode (campaign mode is still broken because it uses generates old style scripts which are not compatible with the new system without a few changes)
_ multiplayer mode
_ saving/restoring games
_ scripting things in COB or Lua (it's possible to extend scripting engine to other languages), but since there is no COB command for anything else than units, you won't be able to script the game or AI with COB scripts
remaining main tasks:
_ create a free HD set of game resources compatible with TA mods (we'll use Lua scripts for this

_ replace FMOD with SDL_mixer
_ replace HawkNL with SDL_net
_ enable compression of networking traffic (not only file transfer)
_ improve networking support (optimize bandwidth usage)
_ create the mod repository system
_ create a global chat system (like battle.net)