Yes, there was a lot of activity.
In the meantime it is a complete product: www.aircine.de
I dont use Arduinos anymore (but i did for a while!), now the
complete arduino schematic is included into the PCB. And i dont
use the ATmega timers anymore for measuring. It works, but
i developed a CPLD and now the measuring is done completely in
hardware. Measurement accuracy of the hardware now is better than
0.5 mm...