CouchApp really is excellent marketing, folks, and I congratulate you. As I'm sure you know, any database with an HTTP interface will do exactly the same thing. Riak, for example. I leave you to your normal round of thoughtful, reasoned NoSQL vs RDBMS debate.
Riak and other HTTP based databases do not have the peer-based replication which sets CouchDB apart. Being able to share an application and its data with a simple HTTP call, and synchronize it across all your phones and laptops -- that is not something other databases can do.
