Thanks that was an interesting read. It's not really related to Conboy, but still interesting. Conboy talks to Ubuntu One not using CouchDB, but using the REST API. The advantage is, that we can also sync to other services which implement this API.
Those are currently:

• Snowy: Open source web service and web interface which you can install on your own servers if you want. Developed mostly be the Tomboy guys. Hopefully soon in beta stage.
• Midgard: Open source content repository which is used as backend for maemo.org in many places. Still needs support for OAuth 1.0a. Will hopefully come soon.
• Ubuntu One: Not open source, but more or less working service from Canonical.

Soon the first two projects (Snowy and Midgard) will offer a hosted service. Snowy will power www.tomboy-online.org and Midgard will offer the service on maemo.org.

There are still bugs with all involved parties, but I would expect something that is ready for production use in about half a year maximum.