Onto the 1.0-9XXX drivers... I have heard no official word on anything recently.
They should be here soon as they need to support the Quadro Plex, which should be shipping anytime. (The Quadro Plex officially supports Linux, and any user that just lays down ~$18k on a graphics solution should have drivers) In addition, the GeForce 7950GT and 7900GS will be shipping today. Perhaps the inaugural Rel90 driver will be out mid-September?
This is a clear guess, but I would imagine no immediate support for X.Org 7.2 with the initial Rel90 drivers. The next versions of Ubuntu and Fedora are coming out in October, and they will ship with X.Org 7.1. SuSE 10.2 seems to be the only MAJOR distribution in the immediate future that will likely adapt X 7.2. So it's just a guess that the support won't come too soon, unless the ABI changes are minimal.
what chance that when nvidia and ati have both released drivers supporting GLX_rtp and SUSE have released a X.org 7.1/2 compliant distro that they will support both AIGLX and XGL?
XGL shouldn't have any problems running with either ATI or NVIDIA's current closed-source drivers. As soon as the new GLX extension is supported with the respective drivers, AIGLX should have no problems running. Was that your question?