Well, the new Smartphone errors tab in GWT has given me 2356 errors to fix (but they are the same errors that were appearing in the normal URL errors before). I'm now receiving around 15 error messages a day.
HTML improvements are down to 97. Most of these are the usual paginated content problems... the new rel next and prev tags don't seem to be making a difference to bring them down.
Still no real change in traffic but I have been seeing an extra 1,000 to 2,000 page views a day. Which is probably due to the new breadcrumb links I've recently implemented.