Douglas, from a user standpoint what changed was adding the KMS graphics feature to the kernel so the command line kernel operates in graphics mode as well as the regular gdm graphics display mode. Presumably this allows faster switching between users and I don't know what else. I never switch between users so I don't get any benefit. Also, switching to the kernel by doing Ctrl-Alt-F1 is faster because there isn't any graphics mode resetting. I only ever do that when I'm attempting to deal with a bug or doing bug reporting. Time saved by not resetting the video graphics mode is miniscule to me.
From the user's view, the kernel graphics mode and the gdm don't seem to be well coordinated at all. The kernel fires up graphics mode, you can tell with the tiny print, then X windows starts later setting the graphics mode again and the two do not seem to be working together so crash!
Developers have also alluded to some future KMS things they want to do that I'm not aware of.
At the moment both my i830 integrated video graphics and my i845G integrated video graphics run with the latest Release Code level of ubuntu, no changes required. Note I only use "quiet" and not "quiet splash" since splash is always the same and does not add any new info, and has a history of causing video graphics problems. So booting up I just look at a black screen with a blinking underline in the top left corner for a few seconds until gdm starts.
First real trouble I had with video graphics was Compiz on Intrepid so it is blacklisted. Compiz is "gdm eye candy" and has nothing to do with my running applications which I do full screen anyway.
Hang in there. Jerry