Comment 23 for bug 834725

I suspect this is likely due to changes in powertop. The same issue was reported by another user as testing feedback for the powertop 2.0 beta release earlier this year:

http://article.gmane.org/gmane.linux.power-management.powertop/1959

I subsequently tested the Natty powertop-1.13-1.1ubuntu1 while running an Oneiric 3.0.0-11.17 kernel and confirm wakeups are being calculated:

     PowerTOP version 1.13 (C) 2007 Intel Corporation

Cn Avg residency P-states (frequencies)
C0 (cpu running) ( 0.7%) Turbo Mode 5.5%
polling 0.9ms ( 0.0%) 2.80 Ghz 0.0%
C1 mwait 0.5ms ( 0.3%) 2.67 Ghz 0.0%
C2 mwait 0.8ms ( 4.0%) 1.87 Ghz 0.9%
C3 mwait 6.4ms (95.0%) 1197 Mhz 93.6%

Wakeups-from-idle per second : 203.8 interval: 15.0s