Last year Dr. Davide Maltoni published a paper (Pattern Recognition by Hierarchical Temporal Memory)[1] comparing the algorithms laid out in Dileep Georges original PHD thesis. The results were pretty impressive. There have been many improvements to the algorithm since then too.
Read the paper; HTM's don't seem to do better than other object recognition algorithms at recognizing shapes, especially because there are visual properties it ignores (curvature, global topological properties, etc.) The accuracy for the picture datasets are only 60-70%. What's interesting about HTM is its generality. I can't judge whether it would be good for the Grok prediction engine, but I know more about image recognition and you definitely don't want to use it for that.
http://bias.csr.unibo.it/maltoni/HTM_TR_v1.0.pdf