GNOME 3.10 is tentatively set to be released on 25 September while this is the first development release due this week (GNOME 3.9.1). With just a little more than one month since the GNOME 3.8.0 release, there isn't too much to look at for the 3.9.1 packages.
The Mutter 3.9.1 release for the window manager just fixes up some memory leaks and has random fixes and clean-ups. The GNOME Shell 3.9.1 release has a bit more meat to it but still isn't too exciting:
- Add additional toggle-overview keybinding
- Disable tray context menu while a notification displays
- Watch GApplication busy state
- Disable style transitions if animations are disabled
- Filter out hidden applications from "Frequent" view
- Fix window previews swapping place randomly
- Add support for serialized GIcons in remote search providers
- Fix hotcorner regression in RTL locales
- Allow some keybindings to work while a top bar menu is open
- Make open-app-menu keybinding a toggle action
- Only recognize common URL schemes in notification messages
- Misc fixes and cleanups
I'm still pouring through the other packages checked in for the imminent GNOME 3.9.1 announcement, but so far there isn't too much to get excited about for the first milestone -- there's still plenty more development releases ahead. The GNOME 3.10 schedule can be found on the GNOME Live Wiki.