Just to confirm that this bug is still not fixed: I just got this report on my up-to-date server. The system was more or less idle with the usual server stuff running (apache, postfix, bind,...).

Dec 24 12:27:59 batleth kernel: [1217678.140504] ------------[ cut here ]------------
Dec 24 12:27:59 batleth kernel: [1217678.140515] WARNING: at /build/buildd/linux-2.6.31/fs/notify/inotify/inotify_fsnotify.c:129 idr_callback+0x49/0x70()
Dec 24 12:27:59 batleth kernel: [1217678.140518] Hardware name: X8STi
Dec 24 12:27:59 batleth kernel: [1217678.140521] inotify closing but id=0 for entry=ffff8801b586bee0 in group=ffff880155c8cc00 still in idr.  Probably leaking memory
Dec 24 12:27:59 batleth kernel: [1217678.140523] Modules linked in: ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs exportfs reiserfs ipt_REJECT xt_multiport ipt_LOG xt_limit xt_state xt_tcpudp iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables psmouse lp serio_raw parport raid10 raid456 raid6_pq async_xor async_memcpy async_tx xor usbhid usb_storage raid1 raid0 multipath linear e1000e
Dec 24 12:27:59 batleth kernel: [1217678.140561] Pid: 14547, comm: gam_server Not tainted 2.6.31-16-server #53-Ubuntu
Dec 24 12:27:59 batleth kernel: [1217678.140564] Call Trace:
Dec 24 12:27:59 batleth kernel: [1217678.140571]  [<ffffffff8105e618>] warn_slowpath_common+0x78/0xb0
Dec 24 12:27:59 batleth kernel: [1217678.140575]  [<ffffffff8105e6ac>] warn_slowpath_fmt+0x3c/0x40
Dec 24 12:27:59 batleth kernel: [1217678.140581]  [<ffffffff81524bc4>] ? wait_for_common+0x124/0x170
Dec 24 12:27:59 batleth kernel: [1217678.140586]  [<ffffffff81153039>] idr_callback+0x49/0x70
Dec 24 12:27:59 batleth kernel: [1217678.140590]  [<ffffffff810538a0>] ? default_wake_function+0x0/0x10
Dec 24 12:27:59 batleth kernel: [1217678.140595]  [<ffffffff81271769>] idr_for_each+0x89/0xe0
Dec 24 12:27:59 batleth kernel: [1217678.140599]  [<ffffffff81152ff0>] ? idr_callback+0x0/0x70
Dec 24 12:27:59 batleth kernel: [1217678.140603]  [<ffffffff81150bb4>] ? fsnotify_put_event+0x44/0x60
Dec 24 12:27:59 batleth kernel: [1217678.140607]  [<ffffffff81152fd2>] inotify_free_group_priv+0x22/0x40
Dec 24 12:27:59 batleth kernel: [1217678.140611]  [<ffffffff81150d13>] fsnotify_final_destroy_group+0x23/0x40
Dec 24 12:27:59 batleth kernel: [1217678.140615]  [<ffffffff81150e18>] fsnotify_put_group+0x98/0xb0
Dec 24 12:27:59 batleth kernel: [1217678.140619]  [<ffffffff8115325f>] inotify_release+0x2f/0x50
Dec 24 12:27:59 batleth kernel: [1217678.140622]  [<ffffffff811201ba>] __fput+0xda/0x1f0
Dec 24 12:27:59 batleth kernel: [1217678.140625]  [<ffffffff811202ed>] fput+0x1d/0x30
Dec 24 12:27:59 batleth kernel: [1217678.140630]  [<ffffffff8111c3f8>] filp_close+0x58/0x90
Dec 24 12:27:59 batleth kernel: [1217678.140634]  [<ffffffff81060487>] put_files_struct+0x77/0xe0
Dec 24 12:27:59 batleth kernel: [1217678.140637]  [<ffffffff8106053f>] exit_files+0x4f/0x60
Dec 24 12:27:59 batleth kernel: [1217678.140641]  [<ffffffff810628cb>] do_exit+0x14b/0x360
Dec 24 12:27:59 batleth kernel: [1217678.140644]  [<ffffffff81062b29>] do_group_exit+0x49/0xc0
Dec 24 12:27:59 batleth kernel: [1217678.140648]  [<ffffffff81062bb2>] sys_exit_group+0x12/0x20
Dec 24 12:27:59 batleth kernel: [1217678.140653]  [<ffffffff81011fc2>] system_call_fastpath+0x16/0x1b
Dec 24 12:27:59 batleth kernel: [1217678.140656] ---[ end trace 61f09b5c1eb9371c ]---
Dec 24 12:27:59 batleth kernel: [1217678.140658] entry->group=(null) inode=(null) wd=4096