Same with CouchDB, which was very fashionable when the article came out.

That was sort of my point -- erlang was fashionable like couchdb, but neither ended up living up to the hype :). In that sense couchdb doesn't count.

We use both Erlang and CouchDB at Cloudant and have great success with both

We use Riak extensively at ideeli. It looks poised to stick around for the long-haul.