But, rather than go back to the drawing board, many people are figuring out alternative way to eke better performance outbid the system, and one approach is to use a sidechain.. sonrsther than process many transactions on the bitcoin network, two parties that transact a lot together might deposit down bitcoin into a side chain and conduct a bunch of transactions there (avoiding the absurd cost and delay of bitcoin) and then when they want to “settle up” they then invoke a balancing transaction on the bitcoin network.

Mastercoin and Counterparty are embedded consensus protocols (or meta-protocols) that use the blockchain to store their transactional data. Bitcoin devs, except Peter Todd who was hired by both teams to help them find a proper solution, are very unhappy, to say mildly, about storing the data on the blockchain. Heated discussions on this topic go on for hundreds of pages on bitcointalk and Mastercoin github issue. Mining pools like Eligius started censoring Mastercoin transactions (not sure if they are continuing with this practice right now, but the operators of this pool are adamant that data do not belong to the blockchain).

@gendal, good question. Think of the identity hash as a bitcoin address, it is indeed public. So to assert anything with this identity you need to sign the object you are creating or changing with the identity’s private key. Specifically it is a private key that corresponds to a public key that you published in your identity’s object (json). The signature is not placed on the bitcoin transaction, as OP_RETURN has only 40 bytes. The signature is added to a [json] object that is modified with this identity. If you see any fault with this, please let me know.
Ethereum, a provider of decentralized platform and programming language that helps running smart contracts and allows developers to publish distributed applications. Factom, a provider of records management, record business process for business and governments. Blockstream, a provider of sidechain technology, focused on extending capabilities of Bitcoin. The company has started experimenting on providing accounting (considered a function to be done on private blockchain) with the use of public blockchain technology.
Fully private blockchains: a fully private blockchain is a blockchain where write permissions are kept centralized to one organization. Read permissions may be public or restricted to an arbitrary extent. Likely applications include database management, auditing, etc internal to a single company, and so public readability may not be necessary in many cases at all, though in other cases public auditability is desired.
The sole distinction between public and private blockchain is related to who is allowed to participate in the network, execute the consensus protocol and maintain the shared ledger. A public blockchain network is completely open and anyone can join and participate in the network. The network typically has an incentivizing mechanism to encourage more participants to join the network. Bitcoin is one of the largest public blockchain networks in production today.