What is a "thread locking means"? Are there currently any covers "listed as providing satisfactory ground continuity between the box and the receptacle"?

Are we talking about the little metal clip on the device yoke that holds the 6/32 screw?

Are you talking about the "self grounding clip"?
I don't think that is what they are talking about. I believe the intent is to prevent the device from loosening up in the cover since the alternative is a rivet.
These are devices in flush boxes that do not require a grounding jumper. Personally I would just lose the whole paragraph and simply require the jumper but they didn't ask me.

Reading this a little more:
It seems to re-address RS covers.
Most I see now have the bolt and nut where the nut has the serrated surface.
So for a duplex recpt. you no longer have just the one 6/32 screw in the middle but now have a bolt and nut for the two attachment locations in the yoke top and bottom.

That is what the proposal to 2011 is saying.