The server runner plugin can now work entirely offline - without connecting to anything remote, not even a master. In such a case it will run using the local files. Basically, running a map is now as easy as entering the name of the map in the GUI and clicking 'start'.
In such a situation you don't have any of the benefits of the master server, like getting the latest version of the game, being able to upload changes, play multiplayer or co-op games, etc. But, it is useful for when you don't have a network connection, for demos, or if you just want to run entirely standalone - like for a singleplayer game.
Speaking of singleplayer games, in a few lines of script the client can now be set up to automatically run a certain map using the plugin, which would basically turn the client into a single-purpose game: Start the client, and that game runs. If you also change the branding (logo, menus, etc.), it is now easy to use the Intensity Engine for your own singleplayer games.
(The underlying functionality for these new features is that you can set [Activity] force_location on the server, and it will run the map with that location, without querying the master. It will also communicate that fact to the client, so it does the same. The server runner plugin basically runs the server in a transparent way, with that feature enabled.)