As a spin-off to that, the ATUSB device was designed: A general-purpose open hardware (and FOSS firmware + driver) IEEE 802.15.4 adapter that can be plugged into any USB port.
This adapter has received a mainline Linux kernel driver written by Werner Almesberger and Stefan Schmidt, which was eventually merged into mainline Linux in May 2015 (kernel v4.2 and later).
Earlier in 2016, Stefan Schmidt (the current ATUSB Linux driver maintainer) approached me about the situation that ATUSB hardware was frequently asked for, but currently unavailable in its physical/manufactured form. As we run a shop with smaller electronics items for the wider Osmocom community at sysmocom, and we also frequently deal with contract manufacturers for low-volume electronics like the SIMtrace device anyway, it was easy to say "yes, we'll do it".
As a result, ready-built, programmed and tested ATUSB devices are now finally available from the sysmocom webshop
Note: I was never involved with the development of the ATUSB hardware, firmware or driver software at any point in time. All credits go to Werner, Stefan and other contributors around ATUSB.