The key features introduced since X.Org 7.4 last year are Multi-Pointer X, X Input 2.0, input device properties, RandR 1.3, and DRI2. If you're not already familiar with these new features, well, you are not reading Phoronix enough. The X.Org 7.5 release announcement can be read on the mailing list with additional information being available from the X.Org web-site.
The next release, X.Org 7.6, will likely come next October. The next X Server release, X Server 1.8, is planned to come out in March.