This happened again, and I was able to get some info from a different TTY. 

Here's the relevant part from /var/log/messages - compiz crashes.

Feb 24 13:17:06 fridge kernel: [349959.691938] compiz.real[22928]: segfault at 5 ip 08055c3c sp bfc0a410 error 4 in compiz.real[8048000+34000]

This bug is actually intermittent - it does not always happen on first login after all. Zapping X sometimes causes it; first login sometimes works fine. Last time that this happened, ctrl alt bksp was not enough to recover from it; I had to completely reboot the machine. I didn't capture Xorg.log from that startup, but my current one is attached.

lsusb:

Bus 002 Device 004: ID 0a12:1004 Cambridge Silicon Radio, Ltd 
Bus 002 Device 002: ID 04f2:0402 Chicony Electronics Co., Ltd 
Bus 002 Device 003: ID 0e9c:0000 Streamzap, Inc. Streamzap Remote Control
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 007: ID 046d:c408 Logitech, Inc. Marble Mouse (4-button)
Bus 001 Device 002: ID 058f:6254 Alcor Micro Corp. USB Hub
Bus 001 Device 004: ID 05e3:0716 Genesys Logic, Inc. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

lspci:

00:00.0 Host bridge: nVidia Corporation C55 Host Bridge (rev a2)
00:00.1 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:00.2 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:00.3 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:00.4 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:00.5 RAM memory: nVidia Corporation C55 Memory Controller (rev a2)
00:00.6 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:00.7 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.0 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.1 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.2 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.3 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.4 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.5 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:01.6 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:02.0 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:02.1 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:02.2 RAM memory: nVidia Corporation C55 Memory Controller (rev a1)
00:03.0 PCI bridge: nVidia Corporation C55 PCI Express bridge (rev a1)
00:07.0 PCI bridge: nVidia Corporation C55 PCI Express bridge (rev a1)
00:09.0 RAM memory: nVidia Corporation MCP51 Host Bridge (rev a2)
00:0a.0 ISA bridge: nVidia Corporation MCP51 LPC Bridge (rev a3)
00:0a.1 SMBus: nVidia Corporation MCP51 SMBus (rev a3)
00:0a.2 RAM memory: nVidia Corporation MCP51 Memory Controller 0 (rev a3)
00:0b.0 USB Controller: nVidia Corporation MCP51 USB Controller (rev a3)
00:0b.1 USB Controller: nVidia Corporation MCP51 USB Controller (rev a3)
00:0d.0 IDE interface: nVidia Corporation MCP51 IDE (rev a1)
00:0e.0 IDE interface: nVidia Corporation MCP51 Serial ATA Controller (rev a1)
00:0f.0 IDE interface: nVidia Corporation MCP51 Serial ATA Controller (rev a1)
00:10.0 PCI bridge: nVidia Corporation MCP51 PCI Bridge (rev a2)
00:14.0 Bridge: nVidia Corporation MCP51 Ethernet Controller (rev a3)
01:00.0 VGA compatible controller: nVidia Corporation G92 [GeForce 8800 GT] (rev a2)
03:06.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet (rev 10)
03:07.0 Multimedia audio controller: Creative Labs CA0106 Soundblaster
03:08.0 FireWire (IEEE 1394): VIA Technologies, Inc. VT6306 Fire II IEEE 1394 OHCI Link Layer Controller (rev c0)