http://www.spamhaus.org/faq/answers.lasso?section=Spamhaus%20DBL#291
quote,
One way to address this problem would have been to treat URL shortener domains the same way as any other spammed domain and include them in our main DBL zone. But, as mentioned, most of these URL shortener serve a legitimate purpose and are used in non-spam emailings. Spamhaus has always worked to avoid the blocklisting of assets that would cause unjustified false positives.
In fact Spamhaus *has* been treating them the same as other domains, and causing false positives on shorteners widely used for legitimate purposes, such as bit.ly, tinyurl.com, fly2.ws, and is.gd. But they've been doing it on the IP-based SBL, not the domain name list. I hope the IP blocks for shorteners will stop. It's degraded the quality of SBL, which in the past was so accurate on spammer-owned hosts that we were willing to 550 based on a match. I could see scoring for shorteners. So this is good news. Joseph Brennan Columbia University Information Technology