Hello, I have done the following upgrade today (Archlinux):

[2011-01-15 16:40] upgraded dri2proto-git (20110107-1 -> 20110114-1)
[2011-01-15 16:40] upgraded git (1.7.3.5-1 -> 1.7.3.5-2)
[2011-01-15 16:40] upgraded glproto-git (20110107-1 -> 20110114-1)
[2011-01-15 16:40] upgraded libdrm-git (20110107-1 -> 20110114-1)
[2011-01-15 16:40] upgraded mesa-full (20110107-1 -> 20110114-1)
[2011-01-15 16:40] upgraded mesa-full-gallium (20110107-1 -> 20110114-1)
[2011-01-15 16:40] upgraded xf86-video-ati-git (20110107-1 -> 20110114-1)

Graphics-Card: Radeon 5650 Mobile

$ glxinfo | grep -i opengl
#a lot of messages like in the following line:
EE r600_asm.c:83 r600_bc_get_num_operands - Need instruction operand number for 0xd6.
OpenGL vendor string: X.Org
OpenGL renderer string: Gallium 0.4 on AMD REDWOOD
OpenGL version string: 2.1 Mesa 7.11-devel
OpenGL shading language version string: 1.20
OpenGL extensions:
ATTENTION: default value of option vblank_mode overridden by environment.

In IOQuake3 and glxgears I got ugly pixel-mud, looks like block-artifacts. With the older git-checkouts from 20110107 I had no problems, everything was right.
Bye

A personal note, I write this caused by the "Attention"-Message above:
Personally I think vblank_mode=0 should be default again, until Tripple-Buffering can be offered. I (and the most other people) doesn't recognize tearing in FPS-Games and other applications, but everyone recognize low framerates! On the other side VSYNC with Double-Buffering leads to massive performance droops and very often to stuttering. Because the OpenGL Performance is simply to low and Double-Buffering is not a solution, it is a ugly workaround ;-)

If VSYNC should be default, we should use generally OpenGL-Tripple-Buffering. Because Tripple-Buffering fixes tearing, with practically no performance impact.