it looks like it's listening... here's a better way to see it:
netstat -an | grep udp | grep 53
on my box (with dnsmasq on it) it looks like this:
win32sux@darkstar:~$ netstat -an | grep udp | grep 53
udp 0 0 0.0.0.0:53 0.0.0.0:*
anyhow, it looks like it's your iptables rules which might be blocking the UDP packets from coming and going... if you post your iptables script i can try and spot the problem for you...
BTW, it seems like you have IPv6 enabled... you might wanna disable that unless you are actually using it...