This will be the first release of major new features since XenForo 1.0. There are lots of things going in, some of which we have hinted at in posts around the forum. There are also a few things that we had originally slated for 1.1 that will now be pushed back to a later release in favour of getting 1.1 out sooner with an array of completed features.
Here are a few features that will be in XenForo 1.1:
Right-to-left layout mode for Arabic (etc.) language support
Thread prefixes, definable at a per-forum and a per-user group basis
Warnings for trouble-making users
Ability for members to ignore other members
Custom user profile fields
Admin CP search
Improved admin and moderator logging
Additional thread viewing permissions
Criteria-based user group promotions
A notice system to display messages to your users in certain circumstances
This is not an exhaustive list. We will expand the feature list over time, but some improvements may be a surprise with the release itself.
We will be detailing many of the features of XenForo 1.1 over time via the Have You Seen...? forum.