Gnome-shell requires acceleration of to work. For this a nvidia card
with the nvidia-driver, or a Intel/ATI KMS enabled card is needed.

For the nvidia users no other changes are needed. For Intel/ATI KMS
driver the user needs to have read/write permissions on
/dev/dri/cardN (usually N=0). If gnome-shell is launched from gdm, the
gdm user also needs this access.

Access can be granted by adding the user(s) to the wheel group or using
a devfs.rules(5) to change the mode of the /dev/dri/card0 on creation. 

	add path 'dri/*' mode 0666 group operator