FWIW, openafs-modules-dkms from debian experimental (1.6.0~pre1-1) builds on 2.6.37-11-generic and 2.6.25-23-generic, but when the module is loaded into 2.6.37-11-generic, it segfaults and pretty much locks up the vfs subsystem.  Here's the segfault from kern.log:

(after # /etc/init.d/openafs-client start )

Jan  3 16:02:39 lynx kernel: [   73.658371] Cache bypass patched libafs module init.
Jan  3 16:02:39 lynx kernel: [   73.699312] enabling dynamically allocated vcaches
Jan  3 16:02:40 lynx kernel: [   73.699321] Starting AFS cache scan...found 0 non-empty cache files (0%).
Jan  3 16:02:40 lynx kernel: [   74.102052] general protection fault: 0000 [#2] SMP 
Jan  3 16:02:40 lynx kernel: [   74.102055] last sysfs file: /sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness
Jan  3 16:02:40 lynx kernel: [   74.102057] CPU 0 
Jan  3 16:02:40 lynx kernel: [   74.102058] Modules linked in: openafs(P) michael_mic arc4 coda ppdev ipmi_msghandler vboxdrv(+) ip6table_filter ip6_tables xt_CHECK
SUM xt_state ipt_REJECT iptable_filter bridge stp kvm_intel kvm dm_crypt snd_hda_codec_realtek snd_hda_intel xt_mark xt_multiport xt_tcpudp snd_hda_codec nvidia(P) 
ipt_MASQUERADE snd_hwdep snd_pcm iptable_mangle btusb iptable_nat nf_nat nf_conntrack_ipv4 snd_seq_midi nf_conntrack nf_defrag_ipv4 lib80211_crypt_tkip bluetooth ip
_tables snd_rawmidi x_tables snd_seq_midi_event wl(P) snd_seq uvcvideo snd_timer snd_seq_device videodev v4l1_compat v4l2_compat_ioctl32 snd soundcore lib80211 snd_
page_alloc shpchp joydev i2c_nforce2 usbhid bcm5974 applesmc input_polldev coretemp nvidia_bl lp parport raid10 raid456 async_pq async_xor xor async_memcpy async_ra
id6_recov hid_apple raid6_pq async_tx raid1 raid0 multipath linear btrfs zlib_deflate libcrc32c uvesafb hid forcedeth ahci libahci [last unloaded: usbhid]
Jan  3 16:02:40 lynx kernel: [   74.102107] 
Jan  3 16:02:40 lynx kernel: [   74.102109] Pid: 2567, comm: afsd Tainted: P      D     2.6.37-11-generic #25-Ubuntu Mac-F2268EC8/MacBookPro5,2
Jan  3 16:02:40 lynx kernel: [   74.102111] RIP: 0010:[<ffffffffa11c3f1f>]  [<ffffffffa11c3f1f>] afs_fill_super+0x5f/0x240 [openafs]
Jan  3 16:02:40 lynx kernel: [   74.102136] RSP: 0018:ffff880105121dc8  EFLAGS: 00010246
Jan  3 16:02:40 lynx kernel: [   74.102137] RAX: ffff880143eb4440 RBX: ffff8801033fb800 RCX: 0000000000000000
Jan  3 16:02:40 lynx kernel: [   74.102139] RDX: ffff880105121fd8 RSI: 0000000000000000 RDI: 0000000000000000
Jan  3 16:02:40 lynx kernel: [   74.102141] RBP: ffff880105121dd8 R08: ffff88014bc18708 R09: 0000000000000000
Jan  3 16:02:40 lynx kernel: [   74.102142] R10: 0000000000000000 R11: 00000000000f4490 R12: ffff88010ef416c0
Jan  3 16:02:40 lynx kernel: [   74.102144] R13: 0000000000000000 R14: ffff8801033fb800 R15: 0000000000000000
Jan  3 16:02:40 lynx kernel: [   74.102146] FS:  00007f55c9d34700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
Jan  3 16:02:40 lynx kernel: [   74.102148] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
Jan  3 16:02:40 lynx kernel: [   74.102150] CR2: 000000000062b668 CR3: 0000000105357000 CR4: 00000000000406f0
Jan  3 16:02:40 lynx kernel: [   74.102151] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Jan  3 16:02:40 lynx kernel: [   74.102153] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Jan  3 16:02:40 lynx kernel: [   74.102155] Process afsd (pid: 2567, threadinfo ffff880105120000, task ffff88010ef416c0)
Jan  3 16:02:40 lynx kernel: [   74.102157] Stack:
Jan  3 16:02:40 lynx kernel: [   74.102158]  0000000000000000 ffffffffa11c3ec0 ffff880105121e08 ffffffff81167acb
Jan  3 16:02:40 lynx kernel: [   74.102161]  ffff88013ad7dd00 ffffffffa11e50a0 0000000000000000 ffff8801073baf40
Jan  3 16:02:40 lynx kernel: [   74.102164]  ffff880105121e18 ffffffffa11c3908 ffff880105121e68 ffffffff8116751d
Jan  3 16:02:40 lynx kernel: [   74.102167] Call Trace:
Jan  3 16:02:40 lynx kernel: [   74.102180]  [<ffffffffa11c3ec0>] ? afs_fill_super+0x0/0x240 [openafs]
Jan  3 16:02:40 lynx kernel: [   74.102185]  [<ffffffff81167acb>] mount_nodev+0x5b/0xa0
Jan  3 16:02:40 lynx kernel: [   74.102196]  [<ffffffffa11c3908>] afs_mount+0x18/0x20 [openafs]
Jan  3 16:02:40 lynx kernel: [   74.102199]  [<ffffffff8116751d>] vfs_kern_mount+0x8d/0x250
Jan  3 16:02:40 lynx kernel: [   74.102202]  [<ffffffff81167754>] do_kern_mount+0x54/0x120
Jan  3 16:02:40 lynx kernel: [   74.102205]  [<ffffffff8118350a>] do_mount+0x1ea/0x220
Jan  3 16:02:40 lynx kernel: [   74.102208]  [<ffffffff81183630>] sys_mount+0x90/0xe0
Jan  3 16:02:40 lynx kernel: [   74.102211]  [<ffffffff8100c0c2>] system_call_fastpath+0x16/0x1b
Jan  3 16:02:40 lynx kernel: [   74.102212] Code: 80 cc 00 00 41 8b 84 24 88 02 00 00 85 ff 89 05 80 5a 03 00 0f 85 63 01 00 00 c7 05 90 5a 03 00 01 00 00 00 48 8b 
05 d9 1f 02 00 <65> ff 00 8b 35 00 be 8b e0 85 f6 0f 85 06 01 00 00 48 89 1d 69 
Jan  3 16:02:40 lynx kernel: [   74.102237] RIP  [<ffffffffa11c3f1f>] afs_fill_super+0x5f/0x240 [openafs]
Jan  3 16:02:40 lynx kernel: [   74.102249]  RSP <ffff880105121dc8>
Jan  3 16:02:40 lynx kernel: [   74.102251] ---[ end trace aeae6251d68abac6 ]---

I have also tried pulling version 1.4.14 from the git source for openafs with the exact same result.  It builds on 2.6.37-11-generic, but segfaults the same way when the module is loaded.