We ourselves only received notification late last evening, and we are trying to find as much as we can right now. Per their notification, they are ceasing operations on Tuesday, 08Feb11. They will continue to provide CertifiedEmail tokens until Tuesday 2/8/11 5pm PST at which time their Token Generators will be taken offline. They also stated that they are "working with our ISP partners to accommodate a transition period for your IP addresses so as to decrease the effort required for warm up. In the meantime, please begin to transition your traffic off of CertifiedEmail."
In the interim, they suggest that you contact customercare@goodmailsystems.com with any and all questions.