Current State: In world but still a lot of work to do.
With 4.1 version skipped, 4.2.0 is the next planned update. It will take a while to get playable at the level of 4.0.6 due to obvious reasons.
Around 520 opcodes have been automapped. The rest will have to be updated manually.
Also there are significant packet structure differences that have to be implemented for some packets.
Starting with 4.2 we are trying a new method of storing opcodes in the DB.
Initial data is in the file emuopcodes.sql which should be applied to the World DB.
This allows easier statistics gathering for things like duplicated opcodes/missing opcodes etc.
Also no rebuild is required for opcode changes which simplifies debugging.
And multiple other tools can access the same table as the core for ease of data sharing.
To simplify updates, a core feature of automatically tracking revisions and applying new ones on startup is planned.
But in the meantime please bear with manually reapplying OpcodesUpdates4.2.0.sql when an update is necessary.
Q: What can I do to help?
A: Provide updated packet structures and missing opcodes.
If you are not a developer, please just wait patiently for it to get playable.
Q: How do I play until then?
A: You can place 4.0.6a executable in the 4.2 WoW folder and use it to start the game.
Q: Is 4.2.0a supported?
A: Yes, there are no important changes compared to 4.2.0