In total, X Server 188.8.131.524 has 81 changes, which consist of CVE security fixes, fixes so the X Server can build properly on the Alpha platform, dropping the GLCore dependency (and move it to dynamic loading), memory leak fixes, and more. With that said, the X.Org 7.4 bug tracker is now cleared out! Unfortunately though, not all of the original bugs were addressed as some were moved to being cleared at a later time (circa X.Org 7.5 in 2009). Building X Server 184.108.40.2064+ now requires building against Mesa 7.1 RC1 or later.
It looks like X.Org 7.4 and X Server 1.5.0 may finally make it out the door in July, not in May as once planned. For the features coming with X.Org 7.4, check out The Progress Of X.Org 7.4. You may also be interested in reading X Server 1.4.1 Is Released, No Joke where we look at the chilling issue of the degrading quality of X.Org releases.
The X Server 220.127.116.114 release announcement (with source download links) can be found on the X.Org mailing list.