From the release notes:
"The new Xorg 1.9 available in Maverick is not compatible with nVidia based chipsets that use the (nvidia-96) and (nvidia-173) drivers."
Hmm that sounded suspicious, didn't I have an nVidia card?
$ sudo lshw -C video
description: VGA compatible controller
product: NV18 [GeForce4 MX 4000]
NVIDIA Driver Version: 96.43.17
Will I be able to test the new release without buying new hardware? It all depends on AaronP now =/