I'm using it and i'm using also uribl as rbl.
It's confirmed on opendns forum if you use OpenDNS dns server and try to lookup uribl they block your connection.
from opendns :
Their response in reply to my question
Subject: DNS Timeouts using your list
Would it be because you are blacklisting their servers?
Correct. We do not answer queries coming from OpenDNS.
They were responsible for over 50 million queries a day hitting our public mirrors, and that is not something we are going to continue to allow.
so, maybe this could be related to SURBL too?? maybe surbl block opendns too..
for now, doesnt use opendns to check rbl/dnsbl as stated in many forum.