Giving a little more time to Oinkfrog I tackled a few things tonight. I changed his mouth bone structure as the existing one meant that any rotation at the centre of the mouth not only applied to the head, but also equally to both sides of the mouth. This meant that having nice mouth shapes flowing all the way to the centre of the mouth wasnt possible.
So I separated the mouth bones from the spine having new bones in the centre parent contrained to the spine and now all is much better behaved and much more usable. I need to fix the weightings to accomodate the new design, but this will be an improvement.
I also created an initial set of eyebrow blend shapes, not only so I can start getting all the detail for them in place, but also to make sure that all the rig deformations work with the blends as well.