I can confirm this bug, using a Sony Vaio VGN-FZ250FE laptop with Ubuntu 8.10 testing.

The kern.log, messages and syslog in /var/log grew to 2048Mb repeating these lines over and over:
Oct 21 18:01:12 BorgClown kernel: [22516.821257]  =======================
Oct 21 18:01:12 BorgClown kernel: [22516.821344] bad: scheduling from the idle thread!
Oct 21 18:01:12 BorgClown kernel: [22516.821347] Pid: 0, comm: swapper Tainted: P          2.6.27-7-generic #1
Oct 21 18:01:12 BorgClown kernel: [22516.821356]  [<c037c3e6>] ? printk+0x1d/0x1f
Oct 21 18:01:12 BorgClown kernel: [22516.821361]  [<c0122b8a>] dequeue_task_idle+0x2a/0x40
Oct 21 18:01:12 BorgClown kernel: [22516.821364]  [<c012107f>] dequeue_task+0xcf/0x130
Oct 21 18:01:12 BorgClown kernel: [22516.821367]  [<c012112a>] deactivate_task+0x1a/0x30
Oct 21 18:01:12 BorgClown kernel: [22516.821371]  [<c037ca03>] schedule+0x4b3/0x790
Oct 21 18:01:12 BorgClown kernel: [22516.821375]  [<c014d3bb>] ? sched_clock_tick+0x7b/0xb0
Oct 21 18:01:12 BorgClown kernel: [22516.821379]  [<c0153dcc>] ? tick_nohz_stop_idle+0x5c/0x70
Oct 21 18:01:12 BorgClown kernel: [22516.821384]  [<c0153e15>] ? tick_nohz_restart_sched_tick+0x35/0x180
Oct 21 18:01:12 BorgClown kernel: [22516.821388]  [<c01028cd>] cpu_idle+0xbd/0x140
Oct 21 18:01:12 BorgClown kernel: [22516.821391]  [<c036edb3>] rest_init+0x53/0x60
Oct 21 18:01:12 BorgClown kernel: [22516.821395]  =======================
Oct 21 18:01:12 BorgClown kernel: [22516.821458] bad: scheduling from the idle thread!
Oct 21 18:01:12 BorgClown kernel: [22516.821461] Pid: 0, comm: swapper Tainted: P          2.6.27-7-generic #1
Oct 21 18:01:12 BorgClown kernel: [22516.821463]  [<c037c3e6>] ? printk+0x1d/0x1f
Oct 21 18:01:12 BorgClown kernel: [22516.821468]  [<c0122b8a>] dequeue_task_idle+0x2a/0x40
Oct 21 18:01:12 BorgClown kernel: [22516.821471]  [<c012107f>] dequeue_task+0xcf/0x130
Oct 21 18:01:12 BorgClown kernel: [22516.821475]  [<c012112a>] deactivate_task+0x1a/0x30
Oct 21 18:01:12 BorgClown kernel: [22516.821478]  [<c037ca03>] schedule+0x4b3/0x790
Oct 21 18:01:12 BorgClown kernel: [22516.821482]  [<c014d3bb>] ? sched_clock_tick+0x7b/0xb0
Oct 21 18:01:12 BorgClown kernel: [22516.821486]  [<c0153dcc>] ? tick_nohz_stop_idle+0x5c/0x70
Oct 21 18:01:12 BorgClown kernel: [22516.821490]  [<c0153e15>] ? tick_nohz_restart_sched_tick+0x35/0x180
Oct 21 18:01:12 BorgClown kernel: [22516.821494]  [<c01028cd>] cpu_idle+0xbd/0x140
Oct 21 18:01:12 BorgClown kernel: [22516.821497]  [<c036edb3>] rest_init+0x53/0x60
Oct 21 18:01:12 BorgClown kernel: [22516.821501]  =======================
Oct 21 18:01:12 BorgClown kernel: [22516.821663] bad: scheduling from the idle thread!
Oct 21 18:01:12 BorgClown kernel: [22516.821666] Pid: 0, comm: swapper Tainted: P          2.6.27-7-generic #1
Oct 21 18:01:12 BorgClown kernel: [22516.821668]  [<c037c3e6>] ? printk+0x1d/0x1f
Oct 21 18:01:12 BorgClown kernel: [22516.821672]  [<c0122b8a>] dequeue_task_idle+0x2a/0x40
Oct 21 18:01:12 BorgClown kernel: [22516.821675]  [<c012107f>] dequeue_task+0xcf/0x130
Oct 21 18:01:12 BorgClown kernel: [22516.821679]  [<c012112a>] deactivate_task+0x1a/0x30
Oct 21 18:01:12 BorgClown kernel: [22516.821683]  [<c037ca03>] schedule+0x4b3/0x790
Oct 21 18:01:12 BorgClown kernel: [22516.821687]  [<c014d3bb>] ? sched_clock_tick+0x7b/0xb0
Oct 21 18:01:12 BorgClown kernel: [22516.821691]  [<c0153dcc>] ? tick_nohz_stop_idle+0x5c/0x70
Oct 21 18:01:12 BorgClown kernel: [22516.821695]  [<c0153e15>] ? tick_nohz_restart_sched_tick+0x35/0x180
Oct 21 18:01:12 BorgClown kernel: [22516.821699]  [<c01028cd>] cpu_idle+0xbd/0x140
Oct 21 18:01:12 BorgClown kernel: [22516.821702]  [<c036edb3>] rest_init+0x53/0x60

Also, the the console terminals are unusable, spitting the same line over and over:
bad: scheduling from the idle thread!

I had to stop the klogd daemon to make it usable again without rebooting. It's only been happening since last week.

As a curiosity, Googling that error message yields only 27 hits.