In the last few months, I've spoken at WPUG, DDD10 and DDD North about Preparing for Windows Phone 8.
Sorry, there's no secrets revealed*. This is all public knowledge and sensible assumptions based on many years of working in the mobile space and with Microsoft products.
Sorry, as with most presentations the slides on their own don't give the full picture but may be useful - and some people have asked for them.
* I know very little that isn't public knowledge and don't have access to the SDK - yet.