My friend Sylvain Berger (who also runs a rendering blog over at http://kobayashystips.blogspot.com/) alerted me to availability of mental ray training over at Digital Tutors.
You can sign up for an account and access a subset of the trainings free of charge as samples. One of these free samples, which Sylvain points out, happens to be a really nice training on using the production shaders in Softimage, which I can recommend.
For those Softimage users who took my masterclass (below) and were annoyed by all the UI happening inside 3ds Max, and wanted to find those equivalent buttons and shaders in Softimage, this training is for you.
/Z