Hi, you are not the first to ask, nor I doubt the last! :) Personally I too would love to see a 'proper' (in the current MS context) TurnKey Domain Controller appliance and obviously that will require Samba4!

But unfortunately all of us here at TurnKey central are very busy with other stuff and while it is on the list, it's not near enough to the top to have any realistic ETA. TBH I couldn't even give you a realistic idea of when we might start working on it, let alone when it might be ready...

I'm not really sure where you're at; but FWIW TurnKey's appliance build infrastructure is open source and publicly available, so if you really wanted to see a TurnKey (Samba4) PDC then it would be super awesome if you made one! If you have a bit of basic Linux knowledge then using TKLDev is fairly straight forward. You will find some info and links to docs and help here. If you head down that path and run into any difficulties, please post here in the forums and I'll do my best to help out.

Also FWIW it looks like Samba 4.1.11 is available in Wheezy backports so if you have a little Debian knowledge (TurnKey v13 is based on Debian Wheezy) then perhaps you could even replace Samba3 in the current PDC with Samba4? I imagine that the config would require a bit of tweaking, but might be worth a shot?!