The big features to the X Input 2.3 update are pointer barrier events and barrier releases. This X Input update once again was largely developed by Peter Hutterer at Red Hat. For going through these new input features for the X.Org Server, he's written a blog post describing pointer barrier events and barrier releases.
The use-cases for pointer barrier events is hot-corners/edges that respond to pushing against them (stemming from GNOME 3.x developer requests) and ad-hoc transparent barriers so depending upon the pointer speed the user can move the barrier (a request by Ubuntu's Unity developers).
X.Org Server 1.14 is expected for release in early March.