This looks a bit different than the original art work and Giovanni says: ”While implemented and working here, may not be ready for 3.6, as it is a bit unstable, and the required configuration bits are not there yet“.
Of course screen lock even without PIN will be included in Gnome 360, if not huge surprises happen!
Next work for Giovanni as he says is: “My plan now? First of all, rebasing all this on the new libgdm (which will require some work to get a testing environment). Then I hope to land this right after 3.5.4, and showcase it at the GUADEC“.