Jon Udell has been focused on education and has produced some great ideas and information about on-demand education. This is an area that I have thought a lot about, here in my blog. There really is a need to better pull together the supply side (training content) and the demand side (people who want to learn certain things).
In the public education arena, we need to "mash-up" of content objectives from the classroom (West Virginia calls the Content Standards and Objectives), teachers lessons (like MathCasts.org, or audio lectures or just comments on how to teach 9th grade Algebra), and the learner profiles/portfolios (along with other stakeholders - the parents). This would/will really provide an incredible support network that will allow for common language, understanding, and feeback loop that just doesn't exist in today's K12 education.
We have also thought about this concept of the professional side. The company I work for has created a new web application that brings together demand and supply, in a totally learner-centric model. It is called LearningFlow. We have just made it available and we are looking for early adopters to give us feedback.
I think there is a lot of thought going on and applications are starting to emerge. On-demand education is not far away.