See http://converter.tipodean.com/unity3d/index.html for details of Tipodean's OpenSim to Collada for Unity3D conversion service.
The Collada translation of the open source OpenVCE assets suitable for import into Unity3D was kindly provided to Austin Tate by Chris Collins of Tipodean Technologies for experiments and an early trial version is available at http://www.aiai.ed.ac.uk/~ai/unity/iroom/collada/
For other experiments with I-Rooms in Unity3D see http://www.aiai.ed.ac.uk/~ai/unity/iroom/
Note that the multi-user severs (using Smart Fox Pro) at Edinburgh are required for some of the demonstrations and are not always left running.
This is an avatar for Ai Austin in Unity3D and using a multi-user approach in an environment created using the OpenVCE OpenSim Archive (OAR) translated to Collada and loaded via Tipodean Technology into Unity3D and delivered via a web browser.