JEEZ...what a name...sounds ominous instead of useful.
The company name is Lattice. Dark Data is a concept.
Based on what little I can find, it looks like these guys specialize data labeling, or maybe unstructured learning (or using one for the other).
When training an AI system, you typically have a "training set" that says "these are all pictures of dogs". When the system studies that set long enough, you can then ask it "does this new picture have a dog in it". The catch is that someone needs to go through all the pictures and find enough with dogs that you can provide as training examples.
This is an incredibly manual, time consuming and error prone process. People are really bad at repetitive mindless tasks. Right now a lot of training sets rely on one of three sources of training data: keyworded data in cloud storage (YouTube, Flickr), Captcha ("prove you're not a robot by finding the pictures of food"), and Amazon Mechanical Turk (farming out to people who get paid 10 cents an image or whatever).
Anything that hasn't run through a system like this, and hasn't been labeled, or at least categorized, is kind of out of the reach of deep learning networks-- it's therefore "dark". Hidden in the shadows.
It sounds like Lattice is trying to further automate the process.