The libGL.so which is installed by the Mesa package does not support DRI
against the current versions of the XFree86 server. Details follow below
(output of glxinfo).

This has been the case both with versions of 4.0.1 out of CVS which I built
myself, and with the latest 4.0.2 release which I built using the source
RPM from rawhide.

DRI works extremely well if the libGL.so from the XFree86 tree is copied to
/usr/lib and the Mesa package version moved out of the way (OK, you also
have to run ldconfig before it'll work). I'm getting a steady almost 30 FPS
in Unreal Tournament with the working version.

[bill@localhost bill]$ glxinfo 
display: :0.0  screen:0
direct rendering: No
server glx vendor string: SGI
server glx version string: 1.2
server glx extensions:
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_EXT_import_context
client glx vendor string: SGI
client glx version string: 1.2
client glx extensions:
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_EXT_import_context, 
    GLX_ARB_get_proc_address
GLX extensions:
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_EXT_import_context
OpenGL vendor string: VA Linux Systems, Inc.
OpenGL renderer string: Mesa GLX Indirect
OpenGL version string: 1.2 Mesa 3.4
OpenGL extensions:
    GL_EXT_abgr, GL_EXT_blend_color, GL_EXT_blend_minmax, 
    GL_EXT_blend_subtract
glu version: 1.1 Mesa 3.4
glu extensions:
    GL_EXT_abgr

   visual  x  bf lv rg d st colorbuffer ax dp st accumbuffer  ms  cav
 id dep cl sp sz l  ci b ro  r  g  b  a bf th cl  r  g  b  a ns b eat
----------------------------------------------------------------------
0x23 24 tc  0 24  0 r  y  .  8  8  8  0  0 32  0  0  0  0  0  0 0 None
0x24 24 tc  0 24  0 r  .  .  8  8  8  0  0 32  0  0  0  0  0  0 0 None
0x25 24 tc  0 24  0 r  y  .  8  8  8  0  0 24  8  0  0  0  0  0 0 None
0x26 24 tc  0 24  0 r  .  .  8  8  8  0  0 24  8  0  0  0  0  0 0 None
0x27 24 tc  0 24  0 r  y  .  8  8  8  0  0 32  0 16 16 16  0  0 0 Slow
0x28 24 tc  0 24  0 r  .  .  8  8  8  0  0 32  0 16 16 16  0  0 0 Slow
0x29 24 tc  0 24  0 r  y  .  8  8  8  0  0 24  8 16 16 16  0  0 0 Slow
0x2a 24 tc  0 24  0 r  .  .  8  8  8  0  0 24  8 16 16 16  0  0 0 Slow
0x2b 24 dc  0 24  0 r  y  .  8  8  8  0  0 32  0  0  0  0  0  0 0 None
0x2c 24 dc  0 24  0 r  .  .  8  8  8  0  0 32  0  0  0  0  0  0 0 None
0x2d 24 dc  0 24  0 r  y  .  8  8  8  0  0 24  8  0  0  0  0  0 0 None
0x2e 24 dc  0 24  0 r  .  .  8  8  8  0  0 24  8  0  0  0  0  0 0 None
0x2f 24 dc  0 24  0 r  y  .  8  8  8  0  0 32  0 16 16 16  0  0 0 Slow
0x30 24 dc  0 24  0 r  .  .  8  8  8  0  0 32  0 16 16 16  0  0 0 Slow
0x31 24 dc  0 24  0 r  y  .  8  8  8  0  0 24  8 16 16 16  0  0 0 Slow
0x32 24 dc  0 24  0 r  .  .  8  8  8  0  0 24  8 16 16 16  0  0 0 Slow