Yes, those are definitely neat. I'll definitely be using the new callouts for tips.
I saw that badges can be made Clickable too, which is great because I've seen a lot of Round X close buttons in corners of windows happening around town. It would be nice to be able to choose the corner though. I've seen them used in the bottom right for large windows in other apps because sometimes content gets pushed out of view at the top.
I can see a lot of usefulness in the new UI attribute as well. Though, after seeing the way you've also shown a way to add a custom-appearance to callouts, I'm wondering if a sample will be made for the Miscellaneous/UI items. It seems we can finally break away from the limitation of themes. It may be a lot of css development work still, but so much better than using a theme-generator. A few dozen settings instead of dealing with a few THOUSAND details.