CommerceBlock has a working MVP used by customers - an invoicing system. They've implemented zero knowledge proofs on the original bitcoin blockchain  but ultimately the underlying technology is blockchain agnostic and can be on any chain that uses homomorphic encryption keys. The invoicing system is a working POC of the underlying protocol layer that will evolve to provide services like derivatives trading, atomic swaps and token/asset creation. They've got a bip under review too. Almost ICO ready