I had some problems to get this thing to work. I followed the instructions from http://welcome.solutions.brother.com/bsc/public_s/id/linux/en/index.html however still the printer did not work correcly. I had to use the following Device URI:
usb://Brother/MFC-7320
for the thing to work (look at lpinfo -v)
On debian lenny, the device URL was correct but I had to create /usr/share/cups/model and reinstall the debian packages to get CUPS to recognize the driver
On Ubuntu 10.04 any user with access to the scanner must be added to the lp group.
To register the device with udev, add /etc/udev/rules.d/scanner.rules with the following contents
# Brother scanners
ATTRS{idVendor}=="04f9", ENV{libsane_matched}="yes"
At least on debian lenny with libsane installed the file is named z60_libsane.rules