I read the announcement at SORBS that they are shutting down on July 20th.  Which would mean anyone who is using them for SpamFilter would need to make some changes.

They also posted an update (at the same page) that states they now may not be shutting down.

With the deadline for them shutting is just a few days away there has been no more updates on their site yet.

If you use their service, it could be important to watch what happens.