A Notary Protocol for the Blockchain

There is a similar service already here http://trustatom.com/

Which in turn seems simliar (albeit more featureful) to http://www.proofofexistence.com/

How is this different from ethereum?

Completely.

Can you elaborate? Can't one implement this in ethereum?

I suppose the fact that this inserts hashes into the Bitcoin Blockchain. makes it entirely different to what ethereum is, that is not to say that something like this could not be implemented using ethereum alone.

We changed the url from http://www.notarychains.com/ since this seems to be where the substance is.