It is Dan's new project. Dan was a co-founder of steemit, and before that, Bitshares. Here is the web site:
http://eos.io/

EOS has not launched yet. it launches Monday at the Consensus 2017 conference. From what I can gather on their Telegram, it is like Etherium in that it has a coin and also can be programmed with Smart Contracts. It allows blockchains to run very fast because it uses all available cores in multi-core processors.

Sign up for the mailing list on their site for more info. Many people expect this to be a great new project with a lot of potential for profit if you get in early. No one knows for sure of course, but we shall see!