apt-get install bridge-utils uml-utilities

/etc/network/interfaces
=======================

# The bridge network interface(s)
auto br0
iface br0 inet static
        address 192.168.3.222
        network 192.168.3.0
        netmask 255.255.255.0
        broadcast 192.168.3.255
        gateway 192.168.3.253
        bridge_ports eth0
        bridge_fd 9
        bridge_hello 2
        bridge_maxage 12
        bridge_stp off

#auto eth0
#iface eth0 inet dhcp

/etc/qemu-ifup
==============

#!/bin/sh
echo "Executing /etc/qemu-ifup"
echo "Bringing up $1 for bridged mode..."
sudo /sbin/ifconfig $1 0.0.0.0 promisc up
echo "Adding $1 to br0..."
sudo /usr/sbin/brctl addif br0 $1
sleep 2

launch
======

iface=""
function cleanup() {
    sudo tunctl -d $iface
    exit 0
}
trap cleanup 1 2 3 15
userid="`whoami`"
iface="`sudo tunctl -b -u $userid`"
args="-hda img"
args+=" -boot c"
args+=" -net nic,vlan=9,macaddr=52:54:00:12:35:09"
args+=" -net tap,vlan=9,ifname=$iface,script=/etc/qemu-ifup"
args+=" -m 256"
args+=" -vnc :49"
args+=" -monitor stdio"
args+=" -S"
qemu $args "$@"
cleanup