Sorry if this was posted before. A friend just updated to the Lumia Black on his 520 (Yes, its being pushed right now) and he has got the awesome Double Tap to wake feature. It is working as it should and the device responds in time.

dtp 520

So the conclusion is that Double Tap is coming to all of the low range Lumia phones as well and is not limited to 625 and 720 as some were predicting. Let’s wait for more 🙂