As messaged to the Karmasphere-Users and Karmasphere-Announce mailing lists, the Karmasphere Reputation Services data feeds are being retired. This means that the associated blacklist(s), including the karmasphere.email-sender.dnsbl.karmasphere.com DNSBL zone, and any other DNSBL/DNSWL zones under karmasphere.com. It is unclear to the author if karmasphere.org is similarly affected.
Karmasphere has indicated that the feed service will be discontinued on November 16, 2009. It's very important that all Karmasphere-using mail administrators remove any Karmasphere-hosted DNSBLs from their configuration before that date, else inbound receipt of legitimate email messages could be delayed or otherwise impacted.
For more information, click on over to Spam Resource to read a copy of the Karmasphere notice.