3D collaborative environment

For a long time many projects have tried to create a functional 3D desktop. Every project that I've seen fails at one point: performance. However, some interesting ideas appear now and then. Recently I've discovered OpenCroquet. It's not a simple 3D desktop. It's more like a 3D world. Croquet is a collaborative 3D environment that allows applications to be shared between several users. And almost any application can run inside Croquet (no need to program it specifically to work in Croquet). Croquet's architecture allows those applications to be shared in a multi-user environment. You can see the application another user is using, and you can even work with him in the same application (see the screenshots). That allows teams far apart to work together in a project.
OpenCroquet is still in early development, although there's already a version for download.