Everything remains open source and community editions remain freely available and fully featured. From that perspective, nothing really changes except each will get the best of what the other has to offer.
It is simple, really: at CouchOne we were 100% committed on the Open Source side of things and at Couchbase we will continue to do so at the same degree. In terms of organisation, Couchbase will be it's own independent Open Source project that has Apache CouchDB and memcached as dependencies, but adds a few things of its own that warrant being its own project. Our combined engineering team, led by Damien, will continue to contribute to Apache CouchDB in the same way as we've been to date, only more.