PKNail is software that is being developed by PointKnown Building Solutions. The purpose of the software is to improve the process of measuring existing buildings and then building a model using Revit.
It's based upon using the Leica Disto D8 surveying tool.
The software is not yet commercially available but I just received an email that shares a video (posted at YouTube) that demonstrates how it works. It is a little over 8 minutes long. If you've ever measured an existing building you might want to spend 8 minutes and watch. Jim Foster is the person doing the demo and he has a blog called BIM, the Built Environment and Stuff. I've embedded the YouTube video here if you want to listen to it now. I recommend watching it full screen though.