Persistent+Sublevel workflow

Was curious, does Unity have a persistent+sublevel workflow similar to UDK? I'm trying to look through the documentation but can't find any.

Basically, in UDK you have a persistent level that is always loaded. (In Unity it'd be the base scene). Then in UDK you also can load or stream in other levels based on particular logic as children of the persistent level (more Unity scenes). These sub-levels would be separate files from the persistent level: http://udn.epicgames.com/Three/LevelStreamingHowTo.html

I know Unity has streaming, but I'm looking for this to help with workflow. E.g. having a different sublevel so someone can work on the audio of the level, the art on the level or the designer driven bits on the level (scripting, etc.). Also another advantage is that these sub-scenes would have a more discreet version history, and multiple people in theory could work on the same overall scene, sync to the latest files and see everyone else's changes.