As is usually the case for X.Org Server point releases, the xorg-server 1.11.3 release just incorporates bug-fixes that have appeared in Git master and elsewhere.
This third X.Org Server 1.11 point release has just about 30 fixes that have appeared in recent weeks, while there's still a handful of known issues.
Details on X.Org Server 1.11.3 are available from this mailing list message.
Meanwhile the next major release of the X.Org Server and one that will bring new features (such as X Input 2.2 / Multi-Touch) is X.Org Server 1.12. This next feature release will come in March.