Just to clear up one point that was semi-made already, "they" meaning Apache CouchDB isn't shifting anything toward mobile. They're still making the same great product from before.
The mobile stuff that you're referring to is CouchBase's. It's a completely different product and their work should not be confused with Apache CouchDB's, though it often is.
Yeah, we call it Incremental MapReduce and we _LOVE_ it. I swear, it's one of the biggest "ah ha!" moments whenever I do training for Cloudant's customers.
The basic idea is that the intermediate Map function results are persisted, while most other system (read: hadoop) throws them out.
To be even more specific while still generalizing, Couchbase is the Membase product with a heavily modified CouchDB swapped in for the storage mechanism (previously SQLite).
As for the leaders, it's a smattering of CouchOne/Couch.io and Membase/Northscale people. Or, as a friend put it, CouchOneBase.io.
The mobile stuff that you're referring to is CouchBase's. It's a completely different product and their work should not be confused with Apache CouchDB's, though it often is.