USB group permissions

[Jannis]

Hey devs,

I've come across several issues when trying to get my USB scanners
ready lately. One of them was that users in group 'usb' have no
read+write access to device nodes /dev/bus/usb/**/*. 

Sane uses libusb to communicate with the scanners I have and libusb
tries to open one of the device nodes mentioned above for reading and
writing. IMHO, adding a user to the 'usb' group should give him/her
permissions to use USB devices like scanners through libusb, which in
turn means that there should be something like an udev rule for:

  1. changing the group of all /dev/bus/usb/**/* nodes to 'usb'
  2. changing the permissions of these nodes at least to g+rw 

What do you think of this?

Regards,
  Jannis