|the original photo is by mauroguanandi on Flickr|
Mulberry is a toolchain and deployment strategy wrapped around PhoneGap. The unofficial description is that it follows a Rails-like approach to the toolchain. As far as deployment is concerned, Mulberry acts as an HTML browser in a private application.
Like Rails, Mulberry is opinionated, and provides generators for scaffolding. It relies upon the exposure of content through a "node" interface to publish data. Several of the artifacts created with the generator are configuration files for things like the media form factors, devices, site map, default content (in markdown), routes, etc. The system is then immediately available to test using "mulberry serve", the built-in server, without a build process. Also like Rails, the system uses special URL formats to convey configuration settings in the running app.
Basically, Mulberry is a single page, off-line application meant for quick deployment.
Mulberry sends most of the content down as a static set of nodes, but the deployment wrapper supports polling for content refreshes. Currently that functionality is limited to content, not including templates or behavior, due to Apple Store guidelines.