Lol, I have rt3090 and I always found that funny (RT3090 firmware is same as
RT2860)
Also: http://www.mediatek.com/en/downloads/rt3090pcie/
and:
http://git.savannah.gnu.org/cgit/linux-libre-fw.git/tree/rt2x00-fw/README
(this is exactly what you were just talking about)
And in the driver, there's a firmware.h which contains the firmware as a
header. That's a GPL incompatibility. I wonder if we could use that to get
them to release the source to the firmware. Save the driver source code just
in case they change it to hide their mistake.