You need at least the rt2570 v1.1.0-b2 or the CVS version.
But you should better use a specially patched one from http://homepages.tu-darmstadt.de/~p_larbig/wlan/.

ifconfig rausb0 down
rmmod rt2570
wget http://homepages.tu-darmstadt.de/~p_larbig/wlan/rt2570-k2wrlz-1.4.9.tar.bz2
tar -xvjf rt2570-k2wrlz-1.4.9.tar.bz2
cd rt2570-k2wrlz-1.4.9/Module
make && make install
modprobe rt2570

Make sure to load the driver with modprobe (not insmod).