We presented our idea about virtual world platforms are only a multipurpose tool. The essential question is how we adapt it for a clear educational purpose with specific educational applications and services. The result should be Massively Multiuser On-line Learning (MMOL) Platforms.
We define MMOL Platform like those mixed, virtual and/or augmented reality environments built on virtual world servers that provide interactive learning by means of 2D, 2.5D, 3D or fully immersive interfaces, appropriate for creating and managing on-line collaborative learning platforms in which individuals will participate in a real or figurative way (avatar).
You can see an extended document about the use of MMOL Platform in this link.