At the moment it's mostly just the remaining things that didn't make it into 1.8. I would ask for more feature requests but I just wanna try and get the current list done first. Which is:
- On-page Notifications
- More control over which pages are displayed (e.g. completely turning off the Users page)
- Allow user to sort answers by votes/time.
- Change user page URLs to /id/username
- Use AJAX for closing questions
There are also a few nice "under-the-hood" changes that have already been made:
- Namespaces used in core code
- New routing and Controller system (work in progress)
- Recalc code converted to OO (thanks to Spudley for this)
- AJAX calls now use JSON responses, and can make updates to multiple parts of a page (excellent work by pupi1985)
I also have a list of over 80 minor things I'd like to do, but I probably won't get around to many of them :)