BT DHT is working. Shareaza uses a separately developed library. See
the readme.
As for G2 DHT and Kad, I think it might be intelligent to implement KAD support first and after doing so, adding G2 DHT. Like this, G2 DHT could profit from the knowledge gained while implementing KAD
and we could also reuse bigger chinks of existing (KAD) code more easily for the implementation of G2 DHT.
Also, it seems to me that KAD would currently give our users a much greater advantage than a new DHT supported by Shareaza only. This is especially true as more and more of the old eD2k servers are failing and due to past misbehavior (real or perceived), Shareaza is banned from quite a lot of the remaining servers. Also, with every new version of eMule and co, more and more users are switching over from the servers to KAD permanently, which effectively makes server based eD2k a dieing network.