It's awesome that Valve is doing this! They have said from the start that they were going to open up Lighthouse (the codename for the tracking system) to hardware manufacturers and this is the first part of that follow-through.
Should be exciting to see what kinds of devices come out of this. I know I saw a few devices (like gloves) at SIGGRAPH that attempted to reverse engineer tracking with the base stations, so this should speed up their development considerably. I wouldn't be too surprised if we see at least an announcement of wireless Lighthouse-tracked gloves for VR by the end of the year.
It's not just controllers or HMDs either. I expect to see a beer coozy with tracking so people can pick up drinks on a desk while remaining in VR, and maybe a collar for pets so you don't step on your dog/cat while the headset is on. The possibilities are endless!