"The meaning of the statement was that NoSQL systems (really the various map-reduce systems) are lacking a standard model for describing and querying and that developing one should be a high priority task for them."
I don't see why the relational model (or some subset thereof) won't work for most NoSQL databases.
Key-Value store? It's essentially just a relational database where tables can have one primary key and one other column.
Document store? Essentially just a dynamically typed relational database.
Graph database? You probably would have to add to the relational model a bit, but Codd did write a bit about recursive queries.