The research is very far from done.
Disclaimer: I'm not a physicist but at the lab the guy to my left is one and he's doing a PhD about memristors. I have an experimental device in front of me with wires coming out and stuff, it's based on some titanium alloy.
They basically don't know why it works. They have some theories, like conductive ion micro channels forming in the material or something like that. They have two mathematical models of simulation, completely different of each other, and each one "works" under different set of conditions, but unlike transistors, flash memory and other components, the underlying effect that make most memristors work is currently unknown or theoretical. I was quite suprised because they don't tell you this in the news.
I'm sure this small detail will not stop HP or Intel from selling it anyway.
Edit: "the concept of a memristor, that of a large amount of small devices storing chunks of a larger piece of memory" <-- this is not the concept of a memristor. Not even close.