1. A development framework, implemented by one or more computer devices, for developing a spoken natural language interface, comprising: a development system, comprising: a developer interface module configured to provide a development interface, the developer interface module comprising: logic configured to receive a set of seed templates, each seed template identifying a command phrasing for use in invoking a function performed by a program, when spoken; and logic configured to collect a set of added templates, each added template identifying another command phrasing for use in invoking the function, the set of seed templates and the set of added templates forming an extended set of templates; a resource interface module configured to interact with one or more development resources to provide the set of added templates; and a data store for storing the extended set of templates associated with the function, the extended set of templates being for use in training one or more models for use on a user device, and said one or more models being for use in interpreting commands spoken by end users.