Alblasco,
my recent reinstall of 12.04 seems to work fine with the bridge setup.
Just after install, I ran the sql command
UPDATE Device_DeviceData SET IK_DeviceData="eth0,dhcp|br0,192.168.80.1,255.255.255.0" WHERE FK_DeviceData=32;
after my bridge was set up, then did an iptables -F followed by '/usr/pluto/bin/Network_Firewall.sh'.
I may not have needed to do all of that, but it works!
Dennis