Things are getting interesting now that more major players start supporting OSL. This week Pixar announced the support for OSL in Renderman and a few months ago Chaosgroup released a version of V-Ray with OSL integration.
Not all integrations are equal, for example the one in Renderman doesn't appear to support closures (bsdf's), but nevertheless, now there is a huge potential to share programmatical patterns and textures between V-Ray, Renderman and Blender. I am quite exited and can't wait to see how this will foster the reuse of shaders across platforms. To illustrate the portability: some of the shaders provided as examples on the V-Ray page work on Blender without a single change, while others need some tweaks, mainly because each renderer provides its own set of closures (for eaxmple, Blender does not have the phong() closure) and more importantly, the output model is not identical: the V-Ray shaders don't provide closure outputs, but simply assign to the
Ci variable, something that on Blender has no effect.