You haven't given any details...  How are you starting compiz?  What distribution are you using?  What errors are getting?

sorry i was gathering some information to attach:

I start compiz with:
export LIBGL_ALWAYS_INDIRECT=1
compiz.real --replace glib gconf

I get:

compiz.real (core) - Fatal: Root visual is not a GL visual
compiz.real (core) - Error: Failed to manage screen: 0
compiz.real (core) - Fatal: No manageable screens found on display :0.0

-----------------------------
The diff between an Xorg.log with the old and new driver is (doing diff -u log.with.compiz.working log.with.compiz.NOT.working)

--- Xorg.0.log	2008-08-24 22:23:35.000000000 +0200
+++ Xorg.0.log.no-compiz	2008-08-24 22:21:30.000000000 +0200
@@ -20,7 +20,7 @@
 Markers: (--) probed, (**) from config file, (==) default setting,
 	(++) from command line, (!!) notice, (II) informational,
 	(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
-(==) Log file: "/var/log/Xorg.0.log", Time: Sun Aug 24 22:22:21 2008
+(==) Log file: "/var/log/Xorg.0.log", Time: Sun Aug 24 22:19:48 2008
 (==) Using config file: "/etc/X11/xorg.conf"
 (==) ServerLayout "Default Layout"
 (**) |-->Screen "Default Screen" (0)
@@ -506,16 +506,16 @@
 (II) RADEON(0): [drm] installed DRM signal handler
 (II) RADEON(0): [pci] 32768 kB allocated with handle 0xf9b11000
 (II) RADEON(0): [pci] ring handle = 0xf9b11000
-(II) RADEON(0): [pci] Ring mapped at 0xb38b0000
+(II) RADEON(0): [pci] Ring mapped at 0xb3725000
 (II) RADEON(0): [pci] Ring contents 0x00000000
 (II) RADEON(0): [pci] ring read ptr handle = 0xf9c12000
-(II) RADEON(0): [pci] Ring read ptr mapped at 0xb8082000
+(II) RADEON(0): [pci] Ring read ptr mapped at 0xb7ef7000
 (II) RADEON(0): [pci] Ring read ptr contents 0x00000000
 (II) RADEON(0): [pci] vertex/indirect buffers handle = 0xf9c13000
-(II) RADEON(0): [pci] Vertex/indirect buffers mapped at 0xb36b0000
+(II) RADEON(0): [pci] Vertex/indirect buffers mapped at 0xb3525000
 (II) RADEON(0): [pci] Vertex/indirect buffers contents 0x00000000
 (II) RADEON(0): [pci] GART texture map handle = 0xf9e13000
-(II) RADEON(0): [pci] GART Texture map mapped at 0xb1a30000
+(II) RADEON(0): [pci] GART Texture map mapped at 0xb18a5000
 (II) RADEON(0): [drm] register handle = 0xdfdf0000
 (II) RADEON(0): [dri] Visual configs initialized
 init memmap
@@ -816,35 +816,27 @@
 (II) RADEON(0): Adding Screen mode: 1280x1024
 (II) RADEON(0): Total number of valid Screen mode(s) added: 1
 (II) RADEON(0): Output: S-video, Detected Monitor Type: 0
-(II) RADEON(0): Output: VGA-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: DVI-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: LVDS, Detected Monitor Type: 0
-in RADEONProbeOutputModes
-(II) RADEON(0): Added native panel mode: 1400x1050
-(II) RADEON(0): Adding Screen mode: 1280x1024
-(II) RADEON(0): Total number of valid Screen mode(s) added: 1
-(II) RADEON(0): Output: S-video, Detected Monitor Type: 0
-(II) RADEON(0): Output: VGA-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: DVI-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: LVDS, Detected Monitor Type: 0
-in RADEONProbeOutputModes
-(II) RADEON(0): Added native panel mode: 1400x1050
-(II) RADEON(0): Adding Screen mode: 1280x1024
-(II) RADEON(0): Total number of valid Screen mode(s) added: 1
-(II) RADEON(0): Output: S-video, Detected Monitor Type: 0
-(II) RADEON(0): Output: VGA-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: DVI-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: LVDS, Detected Monitor Type: 0
-in RADEONProbeOutputModes
-(II) RADEON(0): Added native panel mode: 1400x1050
-(II) RADEON(0): Adding Screen mode: 1280x1024
-(II) RADEON(0): Total number of valid Screen mode(s) added: 1
-(II) RADEON(0): Output: S-video, Detected Monitor Type: 0
-(II) RADEON(0): Output: VGA-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: DVI-0, Detected Monitor Type: 0
-(II) RADEON(0): Output: LVDS, Detected Monitor Type: 0
-in RADEONProbeOutputModes
-(II) RADEON(0): Added native panel mode: 1400x1050
-(II) RADEON(0): Adding Screen mode: 1280x1024
-(II) RADEON(0): Total number of valid Screen mode(s) added: 1
-(II) RADEON(0): Output: S-video, Detected Monitor Type: 0
+(II) AIGLX: Suspending AIGLX clients for VT switch
+(II) RADEON(0): RADEONRestoreMemMapRegisters() : 
+(II) RADEON(0):   MC_FB_LOCATION   : 0x1fff0000 0xd3ffd000
+(II) RADEON(0):   MC_AGP_LOCATION  : 0x27ff2000
+finished PLL2
+finished PLL1
+Entering Restore TV
+Restore TV PLL
+Restore TVHV
+Restore TV Restarts
+Restore Timing Tables
+Restore TV standard
+Leaving Restore TV
+(II) Microsoft Basic Optical Mouse: Close
+(II) UnloadModule: "evdev"
+(II) PS/2 Mouse: Close
+(II) UnloadModule: "evdev"
+(II) AlpsPS/2 ALPS GlidePoint: Close
+(II) UnloadModule: "evdev"
+(II) AT Translated Set 2 keyboard: Close
+(II) UnloadModule: "evdev"
+(II) RADEON(0): [drm] removed 1 reserved context for kernel
+(II) RADEON(0): [drm] unmapping 8192 bytes of SAREA 0xf8825000 at 0xb78fa000
+(II) RADEON(0): [drm] Closed DRM master.

Created attachment 18481 [details]
log of X starting with the new driver (compiz is not able to run with this driver)

I'm actually getting the same thing exactly with a recent mesa build, on my Radeon X700 Mobility. Maybe it's a Mobility thing?

I'm on Gentoo, and update mesa every 2-3 weeks from git. The last update I did broke compiz. As I'm using an ebuild to compile mesa, I'm not sure I can use 'git bisect' so easily, but I'll try to track down which change broke things when I get some free time ( note: I don't get a lot of free time ).

this looks like it may be related to fallout from this:
http://marc.info/?t=121969466200004&r=1&w=2

try reverting 1724334d7c82abe55b6506dfe369df4facae6f06 in mesa or try a newer xserver.

Mass version move, cvs -> git