I actually also get >5% stales using the latest poclbm by luke-jr, catalyst 11.6, sdk 2.4, ubuntu 11.04.
pool.bitp.it:8334 24/07/2011 17:00:42, 67d07587, _rejected_ 48 (Eff:6.73)]
pool.bitp.it:8334 24/07/2011 17:00:50, 79461648, _rejected_ 48 (Eff:6.73)]
pool.bitp.it:8334 24/07/2011 17:06:20, e6223209, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:06:22, baf86b5c, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:06:30, 9b851437, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:06:43, e89b8378, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:06:48, abcbd49d, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:06:55, c97f1d85, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:06:55, 7a1160f0, _rejected_
pool.bitp.it:8334 24/07/2011 17:07:08, 331832ab, _rejected_ 53 (Eff:6.57)]
pool.bitp.it:8334 24/07/2011 17:08:10, b15d15dd, _rejected_ 54 (Eff:6.52)]
pool.bitp.it:8334 24/07/2011 17:08:14, f6cf105d, _rejected_ 54 (Eff:6.52)]
pool.bitp.it:8334 24/07/2011 17:08:19, 586a7649, _rejected_ 54 (Eff:6.52)]
pool.bitp.it:8334 24/07/2011 17:08:20, 96eb1868, _rejected_ 54 (Eff:6.52)]
pool.bitp.it:8334 24/07/2011 17:24:13, long poll: IO error 67 (Eff:6.52)]
pool.bitp.it:8334 24/07/2011 17:24:14, LP connected to pool.bitp.it:8334 67 (Eff:6.52)]
pool.bitp.it:8334 24/07/2011 17:29:32, long poll: new block 0000082b53a84405 71 (Eff:6.49)]
pool.bitp.it:8334 24/07/2011 17:31:36, long poll: new block 00000133afb8a04d 73 (Eff:6.42)]
pool.bitp.it:8334 24/07/2011 17:47:50, 13c9b852, _rejected_ 86 (Eff:6.40)]
pool.bitp.it:8334 24/07/2011 17:52:53, 7b4be65c, _rejected_ 90 (Eff:6.32)]
pool.bitp.it:8334 24/07/2011 17:52:54, d97349df, _rejected_ 90 (Eff:6.32)]
pool.bitp.it:8334 24/07/2011 17:53:01, 26d6fe5c, _rejected_ 90 (Eff:6.32)]
pool.bitp.it:8334 24/07/2011 18:01:41, bdad71cf, _rejected_ 97 (Eff:6.28)]
pool.bitp.it:8334 24/07/2011 18:02:56, a9e1406a, _rejected_ 98 (Eff:6.24)]
pool.bitp.it:8334 24/07/2011 18:03:02, bb5ed498, _rejected_ 98 (Eff:6.24)]
pool.bitp.it:8334 24/07/2011 18:03:05, bb716a04, _rejected_ 98 (Eff:6.24)]
pool.bitp.it:8334 24/07/2011 18:06:31, dd738ad8, _rejected_ 101 (Eff:6.17)]
pool.bitp.it:8334 24/07/2011 18:06:33, 48a73be3, _rejected_ 101 (Eff:6.17)]
pool.bitp.it:8334 24/07/2011 18:06:51, ae570e72, _rejected_ 101 (Eff:6.17)]
pool.bitp.it:8334 24/07/2011 18:11:48, af734db8, _rejected_ 105 (Eff:6.21)]
pool.bitp.it:8334 24/07/2011 18:11:50, bc0b4856, _rejected_ 105 (Eff:6.21)]
pool.bitp.it:8334 24/07/2011 18:14:21, d1c9c700, ERROR (will resend) 107 (Eff:6.13)]
pool.bitp.it:8334 24/07/2011 18:21:59, 1586401f, _rejected_ 113 (Eff:6.13)]
pool.bitp.it:8334 24/07/2011 18:22:01, c3ea8f62, _rejected_ 113 (Eff:6.13)]
pool.bitp.it:8334 24/07/2011 18:22:08, 6c63d1bb, _rejected_ 113 (Eff:6.13)]
pool.bitp.it:8334 24/07/2011 18:31:37, long poll: IO error 121 (Eff:6.15)]
pool.bitp.it:8334 24/07/2011 18:31:38, LP connected to pool.bitp.it:8334 121 (Eff:6.15)]
pool.bitp.it:8334 24/07/2011 18:35:08, long poll: new block 000004a6b287b636 124 (Eff:6.14)]
pool.bitp.it:8334 [373.537 MH/s (~396 MH/s Eff:6.92)] [Rej: 42/812 (5.17%)] [GW: 125 (Eff:6.16)]