XGE is the X Generic Event extension, which is required for MPX support, but these events can also be used by other extensions. The XACE framework is for handling security policy extensions. Parts of XACE have been in the server since X.Org 7.2 but it's not fully implemented and lacks the loadable security modules. For X.Org 7.4 there are XACE modules planned for at least SELinux and Solaris Trusted Extensions.
RandR 1.2 is currently the latest and greatest Reside and Rotate extension, but RandR 1.3 is planned for the future with GPU object support. RandR's GPU object is designed to be another layer between the X screen and the CRTCs. The PCI rework involves using the libpciaccess library, and some of the open-source X.Org drivers (such as the Avivo driver) already utilize this new library.
Next up is Glucose, which is an OpenGL based acceleration architecture that will be hooked into the X server and its acceleration is done using the same paths as XGL. Glucose is designed to work with AIGLX as it provides a convenient way of accelerating common rendering primitives.
Previously we reported that Multi-Pointer X Support would arrive for X.Org 7.4, however, according to the Wiki page that is now on the table for X.Org 7.5. Also planned for X.Org 7.5 is pushing Distributed Multihead X (DMX) up to DIX. Multi-Pointer X Support provides multiple cursor and keyboard support in X. MPX does allow for multi-pointer interaction with legacy applications while also allows for new and more innovative applications.
Like any software project, these current features planned for X.Org are tentative and subject to change and is just some of the work going into X.Org. At the same time, there has been concerns over the degrading quality of X.Org releases so hopefully X.Org 7.4/7.5 will mark the beginning of greater quality assurance work prior to the release. Additional details can be found from the XDS 2007 Notes.