[HTC One X] AcoQ:
Did that twice, results look like this:

Plug pulled at 15:39

[ 03-26 15:39:00.037 463: 515 D/PowerManagerService ]
acquireWakeLock(415967c0): PARTIAL_WAKE_LOCK , tag=AlarmManager, flags=0x1, pid=463, uid=1000, mUserState=0x3

[ 03-26 15:39:00.047 463: 515 V/AlarmManager ]
sending alarm PendingIntent{4182c148: PendingIntentRecord{41890d00 android broadcastIntent}}, intent=android.intent.action.TIME_TICK, type=RTC, count=1, when=1364308740000, repeateInterval=0

[ 03-26 15:39:00.142 463: 485 D/PowerManagerService ]
releaseWakeLock(415967c0): PARTIAL_WAKE_LOCK , tag=AlarmManager, flags=0x1

[ 03-26 15:39:02.272 463: 545 D/StateMachine ]
handleMessage: E msg.what=131155

[ 03-26 15:39:02.272 463: 545 D/StateMachine ]
processMsg: ConnectedState

[ 03-26 15:39:02.277 463: 545 D/WifiStateMachine ]
ConnectedState{ what=131155 when=-4ms target=Handler (com.android.internal.util.StateMachine$SmHandler) {418c0fb8} arg1=5 }

[ 03-26 15:39:02.277 463: 545 D/StateMachine ]
processMsg: L2ConnectedState

[ 03-26 15:39:02.277 463: 545 D/WifiStateMachine ]
L2ConnectedState{ what=131155 when=-5ms target=Handler (com.android.internal.util.StateMachine$SmHandler) {418c0fb8} arg1=5 }

[ 03-26 15:39:02.277 566: 566 D/wpa_supplicant ]
wpa_s 0x41caa6a8 cmd SIGNAL_POLL

[ 03-26 15:39:02.277 566: 566 D/wpa_supplicant ]
RX ctrl_iface - hexdump(len=11): 53 49 47 4e 41 4c 5f 50 4f 4c 4c

[ 03-26 15:39:02.277 566: 566 D/wpa_supplicant ]
ctrl_iface: SIGNAL_POLL

[ 03-26 15:39:02.287 566: 566 D/wpa_supplicant ]
nl80211: survey data missing!

[ 03-26 15:39:02.297 463: 545 D/WifiStateMachine ]
fetchRssiAndLinkSpeedNative RSSI = -55

[ 03-26 15:39:02.297 566: 566 D/wpa_supplicant ]
wpa_s 0x41caa6a8 cmd SignalStrength 7

[ 03-26 15:39:02.297 566: 566 D/wpa_supplicant ]
RX ctrl_iface - hexdump(len=16): 53 69 67 6e 61 6c 53 74 72 65 6e 67 74 68 20 37

[ 03-26 15:39:02.297 566: 566 D/wpa_supplicant ]
ctrl_iface: SignalStrength 7

[ 03-26 15:39:02.297 566: 566 D/wpa_supplicant ]
SignalStrength: =7

[ 03-26 15:39:02.327 463: 545 D/StateMachine ]
handleMessage: X

Plug pulled at 15:50:30

[ 03-26 15:50:31.821 439: 539 D/StateMachine ]
handleMessage: E msg.what=131155

[ 03-26 15:50:31.821 439: 539 D/StateMachine ]
processMsg: ConnectedState

[ 03-26 15:50:31.821 439: 539 D/WifiStateMachine ]
ConnectedState{ what=131155 when=-5ms target=Handler (com.android.internal.util.StateMachine$SmHandler) {416cdc68} arg1=5 }

[ 03-26 15:50:31.821 439: 539 D/StateMachine ]
processMsg: L2ConnectedState

[ 03-26 15:50:31.821 439: 539 D/WifiStateMachine ]
L2ConnectedState{ what=131155 when=-6ms target=Handler (com.android.internal.util.StateMachine$SmHandler) {416cdc68} arg1=5 }

[ 03-26 15:50:31.821 563: 563 D/wpa_supplicant ]
wpa_s 0x407d56a8 cmd SIGNAL_POLL

[ 03-26 15:50:31.821 563: 563 D/wpa_supplicant ]
RX ctrl_iface - hexdump(len=11): 53 49 47 4e 41 4c 5f 50 4f 4c 4c

[ 03-26 15:50:31.821 563: 563 D/wpa_supplicant ]
ctrl_iface: SIGNAL_POLL

[ 03-26 15:50:31.831 563: 563 D/wpa_supplicant ]
nl80211: survey data missing!

[ 03-26 15:50:31.836 439: 539 D/WifiStateMachine ]
fetchRssiAndLinkSpeedNative RSSI = -45

[ 03-26 15:50:31.836 563: 563 D/wpa_supplicant ]
wpa_s 0x407d56a8 cmd SignalStrength 7

[ 03-26 15:50:31.836 563: 563 D/wpa_supplicant ]
RX ctrl_iface - hexdump(len=16): 53 69 67 6e 61 6c 53 74 72 65 6e 67 74 68 20 37

[ 03-26 15:50:31.836 563: 563 D/wpa_supplicant ]
ctrl_iface: SignalStrength 7

[ 03-26 15:50:31.836 563: 563 D/wpa_supplicant ]
SignalStrength: =7

[ 03-26 15:50:31.851 439: 539 D/StateMachine ]
handleMessage: X

Disabled WiFi to see whether there was some fault, no effect _however_ I noticed something else: If I pull the plug but leave my finger on the display and/or rub it around, the device stays responsive and awake. As soon as I lift my finger, even when it's really quick to tap something, the device freezes.

This weird behaviour definitely makes it a power manager issue in my opinion. I have this weird idea that the CPU might go to a ridiculously low level as soon as power is disconnected and no finger keeps the device awake, but I don't know what to do with that idea.