I used to be a Notes Developer (i.e. wrote Notes applications, rather than wrote the code for Notes itself). From what I remember, replication used to take place in the background. You'd refresh your document view (or whatever) and new documents would appear.

If two people were editing the same document in different replicas of the same database, then you would get two copies of the document with one labelled as a "replication or save conflict".

Domino databases have always been fully accessible to applications during replication.

Couchdb and Cloudant are awesome awesome databases, and I'm staggered that they have a legacy of any kind from Notes shocked