Alan Coopersmith, the X.Org wrangler at Sun/Oracle, has done some X.Org 7.6 planning on the xorg-devel mailing list. On the date of the xorg-server 1.9 release, which is scheduled on the 20th of August but could potentially slip by a few days, all driver and protocol updates needed for the 1.9 release should also have been released. At this point, Alan would also like the first release candidate of Xlib 1.4.0 to be tagged.
Around the 31st of August, there should be a feature freeze for all X.Org katamari modules and the module maintainers should begin releasing source packages they would like tested for inclusion into the official 7.6 package set. At the end of the X Developers' Summit in France, which is taking place in the middle of September, there should be X.Org 7.6 RC1 and Xlib 1.4.0 final should be released.
Last but not least, Alan is planning for the X11R7.6 final release to come in early-to-mid October and at the same time there should be an X.Org Server 1.9.1 release to incorporate any bug/regression fixes that made it into the 1.9.0 build.
Some of the changes since the release of the X.Org 7.5 katamari that occurred last October is the inclusion of XCB (the X C Bindings), documentation updates, updated drivers, major configure/Makefile clean-ups and improvements, and most prominently the features that have been delivered with the X Server 1.8 and forthcoming X Server 1.9 releases. Many distributions are already shipping with the individually updated X.Org packages, so again the 7.6 katamari itself isn't too important from at least the end-user perspective. This is also likely to be the first katamari release that would be done on time (X.Org 7.5 was supposed to come last April) after beginning a good track record for releasing close to on time with the xorg-server 1.8 and now 1.9 releases, following a new development process.