Rosetta is an initiative, Application Programming Interface (API) specification and tooling created by the developers at Coinbase aimed at standardising and simplifying the integration of cryptocurrency projects into exchanges and simplifying the building of wallet and related blockchain applications.
The Rosetta Stone - the stone tablet that enabled archaeologists to translate the heiroglyphics found all over ancient Egyptian ruins.
It is only really an API specification, in order to use it, developers of a cryptocurrency either have to add it to their nodes' RPC functionality, or to build a middleware adapter server that talks Rosetta to clients and acts as an intermediary to the full node.
I am now on my second day working on a Rosetta implementation, I have now built the basic deployment Dockerfile according to the 'expectations' specification. I am quite familiar with building Go applications that run other applications (in fact, I build an automatic configuring local multicast mining protocol for Parallelcoin at the end of last year, that runs a miner controller which runs any number of single-thread CPU mining processes), and now have the basic skeleton together so I can start on the actual Rosetta middleware application.
I am not sure how many other exchanges than Coinbase are adopting it, but hopefully within a month or two I will have a fully compliant implementation, which will include the special features for forum posting and voting and the special staking smart contracts in the Blurt blockchain. I would suspect that the Rosetta initiative will gain a lot of ground in the near future and likely this will facilitate the furthering of exposing Blurt to the process of price discovery in centralised exchange services, by lowering the cost of deploying the servers they require in order to list us.
It will also ultimately simplify both Steem and Hive's process to build such integration, as well as the other Steem ports out there, and once they do their implementations, we will much more simply be able to build an application that allows users to use all of the platforms within one neat little one-stop-shop.