Solved! From a more recent & updated Phone wiki:
http://wiki.maemo.org/Phone_control

1.7.3 Query Devlock State

related:

1.7.2 Unlock (pop up lockcode requester?)
1.7.4 Lock screen and keys (slider lockswitch)
1.7.5 Unlock screen and keys
1.7.6 Query lock state of screen and keys

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