The Cisco-owned Spamcop.net spam reporting and blocking list service ran into a bit of trouble this weekend as their "spamcop.net" domain name was allowed to expire. The domain's DNS records reverted to some default "parking" setting by (I think) their domain registrar, which resulted in a wildcard DNS listing, which resulted in a "blocklisting all of the world" scenario for a period of time. I'm not exactly sure when it started, but it was resolved sometime on Sunday.
The Register's Iain Thomson has more info here, if you're curious.
While mentioning Spamcop, I think it's important to remind folks that most ESPs do not actually reject Spamcop reports -- Spamcop disallows sending spam reports to ESPs in many instances, and provides a confusing error message that falsely suggests that the inability to send a report was based on a choice made by the ESP. For more information, click here.