James (acronym for Just A Miniature Entertainment System) is an application providing a home entertainment solution. It is also called James as it aims to be a global "butler" application providing various services. What functionality is actually offered by James also depends on the actual hardware present in the system.
Rationale for calling it Miniature, is because the system will be small in physical size (but not in functionality). Aim is also to reuse as much open source software as possible.
And actually entertainment system is a little bit of a misnomer. James will provide all kind of home services, so it could also e.g. provide NAS functionality or even a web server.