Jul 20 16:39:17 gibson kernel: printing eip:
Jul 20 16:39:17 gibson kernel: c0110cac
Jul 20 16:39:17 gibson kernel: Oops: 0002
Jul 20 16:39:17 gibson kernel: CPU: 0
Jul 20 16:39:18 gibson kernel: EIP: 0010:[add_wait_queue_exclusive+28/48]
Jul 20 16:39:18 gibson kernel: EFLAGS: 00210086
Jul 20 16:39:18 gibson kernel: eax: d1ffe828 ebx: 30ffe828 ecx: 00200286 edx: d6cb7e64
Jul 20 16:39:18 gibson kernel: esi: d6cb7e5c edi: d6cb6000 ebp: d74ba540 esp: d6cb7e44
Jul 20 16:39:18 gibson kernel: ds: 0018 es: 0018 ss: 0018
Jul 20 16:39:18 gibson kernel: Process sendmail (pid: 11458, stackpage=d6cb7000)
Jul 20 16:39:18 gibson kernel: Stack: d1ffe81c d6cb7e5c c01059d1 d6cb7ec4 d1ffe7c0 d1ffe81c 00000001 d6cb6000
Jul 20 16:39:18 gibson kernel: d1ffe828 30ffe828 c0105b44 d1ffe81c d7f00000 d74ba540 c01e6c6b d6cb7ec4
Jul 20 16:39:18 gibson kernel: 00000000 d74ba540 d6cb7f84 c013720c d74ba540 d6cb7ec4 00000004 d6cb7f84
Jul 20 16:39:18 gibson kernel: Call Trace: [__down+65/160] [__down_failed+8/12] [stext_lock+2219/4864] [path_walk+556/1936] [vfs_follow_link+231/352] [ext2_follow_link+23/32] [path_walk+1674/1936]
Jul 20 16:39:18 gibson kernel: [open_namei+134/1424] [filp_open+59/96] [sys_open+56/192] [system_call+51/56]
Jul 20 16:39:18 gibson kernel:
Jul 20 16:39:18 gibson kernel: Code: 89 13 51 9d 5b 5e c3 8d b6 00 00 00 00 8d bc 27 00 00 00 00

Ouch. Luckily for me, the SAK let me reboot without borking my file system.

What can cause this? It crashed just as I was sending an email message (to a reporter, no less-- way to sound professional, Evan!).
Recent changes:
- New RAM (256mb).
- I2C/lm_sensors modules (CPU/fan heat/voltage detection).

I've removed the modules, and I'm hoping it was that.
Could it be that my swap space is too small, now? I had 128mb of swap before, and I now have 384mb of RAM.