Microsoft has released the new version of the KinectSDK Beta 2:
The changelog says nothing about the minimum depth threshold, is it still 850mm?
Eddy Escardo-Raffo wrote in the KinectSDK forum on October 24, 2011 that they have prioritized the request to make the minimum depth value configurable. The forum post ist here.
So maybe it'll be possible in the next version.
I've tested the Beta 2 on my Laptop and it did not return any depth value below 800mm.
PS. Here's a interview with Rob Relyea about the new Beta. The interviewer might actually have mentioned Candescent NUI on CodePlex at the very end, though he didn't say a name :-)