The actual biggest innovation in online learning isn't an innovation, it's the ACCEPTANCE of online learning. Any numbers of studies have been published that show online learning can be as effective as in the classroom, and hybrid classroom/online models can be more powerful than just the classroom. The unimpressive reality is that much of what is called "online learning" is just a course delivered online through a relatively mundane Learning Management System (ala Blackboard, eCollege.) It's taken so long for this to be accepted, that this acceptance is the primary driver in the market of innovation right now.
There's one other preface - the INTERNET is the innovation that matters, no matter the product or content. It gets information and capabilities into the hands of people. We're all just waiting around for the right products to come along to make it easier than reading the entire Internet.