ARTELLA is (from their web) an attempt to "solve the complex challenge of building creative projects through distributed collaboration." by allowing anyone to set up his own virtual distributed studio, initially free, and soon on a low per user fee.
I find the information in their web maybe too scarce, hopefully the video inserted below and this article in AWN will give you enough detail to get an idea:
This video shows the creation of a 3D asset in Artella.
Artella´s blog is also worth mentioning, with a plethora of posts related to the creative and organizational aspects of distributed animated content creation.