I tryed to use X Window Server on VServer guest.
My graphics card was i945.

  1. create vserver guest.
  2. install xserver-xorg in vserver guest.
  3. install libgl1-mesa-dri (for compiz).
  4. edit /etc/vservers//bcapabilities.

CAP_SYS_RAWIO
CAP_SYS_ADMIN
CAP_SYS_RESOURCE
 
CAP_IPC_LOCK
CAP_IPC_OWNER
 
CAP_NET_RAW
CAP_NET_ADMIN
 
CAP_MKNOD

5. create symlink.

# ln -s <GUESTROOT>/etc/modprobe.d/i915-kms.conf /etc/modprobe.d/i915-kms.conf

6. append KMS config to /etc/default/grub.

GRUB_CMDLINE_LINUX_DEFAULT="i915.modeset=1"

7. update grub.

# update-grub

8. reboot!

Enjoy hacking on GUI!