That ATI driver doesn't appear to have any OpenGL 3.0 support as it is missing the extension required to create an OpenGL 3.0 context, GLX_ARB_create_context. Of course, I wouldn't expect it to be there as the specification was only completed on October 22, the day before NVIDIA released their OpenGL 3.0 driver.
Awesome, now provide a driver that can be installed on any kernel and won't break with a switch between kernels, a true Linux kernel module that's actually modular, so normal users who don't understand the risk of installing the binary from Nvidia who then do a system update only to find their system totally hosed after it installed a newer kernel for them won't get fXXXed. Maybe the kernel module API needs some stabilization for that to happen, but regardless something needs to happen because it's a problem for many users.
Well Xserver 1.5 support for GeForce 5 and newer exits since end of may (173.14.xx) - ATI has a beta version since mid of october for Ubuntu. That's in best case 4 month after NV. That change was really more important. Smaller kernel ABI changes can be fixed manually, for bigger ones you need new drivers. For 2.6.28 take a look there: