Accelerometer stops delivering samples when the screen is off on Droid/Nexus One even with a WakeLock

I have some code that extends a service and records onSensorChanged(SensorEvent event) accelerometer sensor readings on Android. I would like to be able to record these sensor readings even when the device is off (I'm careful with battery life and it's made obvious when it's running). While the screen is on the logging works fine on a 2.0.1 Motorola Droid and a 2.1 Nexus One. I have some code that extends a service and rec