Good news on that front - our source code audit is nearly complete, meaning we will be open-source in the very near future. We'll post here as soon as you can access the code.
In the meantime, we have our Documentation available here:
http://docs.nubits.com/, and our NuBitsj library here:
https://github.com/Cybnate/NuBitsjShoot us a message if we can be of help! info at nubits dot com.
I'm a little worried about NubitsJ. Since Nubits uses PoS, the blockchain can't be safely verified by an SPV client. It seems that NubitsJ tries to solve that by trusting a centralized server for blockchain download, which is very insecure (full trust is being placed in that server).
If a more secure model can be worked out, I will work on adding Nubits. This might involve a client with a little more overhead than SPV (e.g. a pruned full-node).